The first beavers in Northumberland for more than 400 years have been stupendously busy. There are new dam systems, as well as canals and burrows, new wildlife-rich wetlands and, thrillingly, a baby beaver.

Whether it is male or female remains to be seen. “Beavers don’t have external genitalia,” said Heather Devey, an expert. “They are really hard to sex. It’s really only through their anal glands that you can tell.”

The National Trust has not yet done that check but it is overjoyed by the birth and the wider benefits one year on from the release of a family of four Eurasian beavers on the Wallington estate in Northumberland.

Paul Hewitt, the countryside manager for the trust at Wallington, said their impact on the estate’s environment had been “astonishing”.

He said: “This time last year I don’t think I fully knew what beavers did. Now I understand a lot more and it is a massive lightbulb moment. It is such a magical animal in terms of what it does.”

On Friday the Guardian joined a beaver safari, and while there were no actual beavers to fawn over – they are nocturnal – there was lots to see in terms of their positive effect on the habitat.

It is just one adult pair doing the work but already the beavers have dramatically changed water levels by creating wildlife-rich wetlands.

Hewitt said the dam-building work of the beavers had helped to create ponds, pools and mudscapes covering an area half the size of a football pitch.

All of it was positive, he said. The new ecosystems are attracting so much more wildlife, including kingfishers, grey herons and Daubenton’s bats, which feed in the ponds and pools.

He added of the beavers: “They have been gone for 400 years and you soon realise what we have been missing as a result.”

Beavers were once a mainstay of British rivers but were hunted to extinction about 400 years ago for their fur and meat, and also for their anal scent glands which produce castoreum, which is said to taste like vanilla.

For beaver lovers the hope is that successful small reintroduction projects such as the Wallington one will persuade authorities to allow much bigger rewilding schemes.

Campaigners have said beavers make a genuine difference to the countryside, boosting wildlife and increasing the landscape’s resilience to the climate crisis.

Devey is a co-founder of the not-for-profit group Wildlife Intrigue, which has been organising small beaver safaris at Wallington. She said visitors went away feeling more optimistic about the vast environmental challenges the world faces.

“That’s why beavers are great. There is so much understandable doom and gloom around – we’re in a climate crisis, a biodiversity crisis – but beavers provide a really positive outlook for the future, they can become an ally,” she said.

The beavers released last year were two adults and two kits. The trust would like to say it knows they are all there but since the animals don’t come out for group photographs, it said it would be no surprise if a young male had moved on.

Hewitt said there had been stories of a beaver being spotted in the River Derwent. “We’re not sure if it’s ours or not,” he said. “Our beaver is tagged and chipped but we’re not sure.”

If it is, it would have had to take a waterway route of an estimated 60 miles.

There were also stories last month of a beaver being seen in the Grand Union canal in Wolverhampton, which is far less likely to be from Northumberland.

Hewitt said the reintroduction of beavers had been his career’s proudest achievement – and he wants everyone to love them.

“Beavers are changing the landscape all the time, you don’t really know what is coming next and that probably freaks some people out,” he said. “They are basically river anarchists.”

As part of his role as UN rapporteur for environmental defenders, Michel Forst has been watching proceedings against climate activists at courts across Europe.

But he may not have seen anything like what unfolded at Southwark crown court in London over the past two and a half weeks, where five Just Stop Oil activists were convicted for conspiring to cause gridlock on the M25 in November 2022.

On the days Forst visited, he witnessed three of the five defendants being arrested in court and dragged to the cells, protesters outside attempting to warn jurors they were not hearing the full case and a judge desperately trying to maintain control over his courtroom.

The judge, Christopher Hehir, had ruled that information about climate breakdown could not be entered into evidence, and could only be referred to by defendants briefly as the “political and philosophical beliefs” that motivated them – which he would tell the jury were in any case irrelevant to their deliberations.

But the defendants had other plans. They sought to turn Hehir’s court into a “site of civil resistance”, causing as much disruption as necessary to ensure that if the jury could not see their evidence on climate breakdown, then the jurors could at least be in no doubt it was being kept from them.

By the time the jury retired to consider a verdict, police had been called into court no fewer than seven times, four of the five defendants had been remanded to prison and 11 others were facing contempt of court proceedings for protests outside the courtroom.

Roger Hallam, Daniel Shaw, Louise Lancaster, Lucia Whittaker De Abreu and Cressida Gethin were standing trial on charges of conspiracy to cause a public nuisance, accused of being the “queen bees” behind a series of protests on the M25.

Under the banner of the climate campaign group Just Stop Oil, already notorious for its road-blocking protests, they were said to have recruited 64 people to climb gantries over London’s orbital motorway, forcing police to stop traffic on four consecutive days.

The prosecution said the disruption amounted to £750,000 of economic damage and a £1m policing cost, with about 709,000 drivers affected. The judge warned the defendants they faced a harsh penalty if convicted.

Two men who blocked the Queen Elizabeth II bridge the month before the gantry protests were jailed for two years each, sentences Hehir said he would take as a reference point.

But why was Forst there in the first place? What can only now be reported is that he had made an extraordinary intervention on the eve of the trial, issuing a public statement criticising the treatment of Shaw in particular. As he awaited trial, Shaw had already spent more than 100 days on remand, been forced to wear an ankle tag, made subject to a strict curfew and banned from meeting his co-defendants or attending environmental demonstrations.

Forst’s intervention came amid increasing alarm at tightening restrictions on protest rights. In the past two years, the UK government has passed two wide-ranging laws targeting direct actions by climate activists, creating a host of new offences with potentially stiff penalties. At the same time, with juries having repeatedly acquitted defendants prosecuted for climate and other protests on the basis that their cause was just, the attorney general had applied to the court of appeal to limit the kinds of defences available in such cases.

Forst had already written to the UK government to express concern over these developments, but issued his latest statement after getting no response. “I fail to see how exposing Mr Shaw to a multiyear prison sentence for being on a Zoom call that discussed the organisation of a peaceful environmental protest is either reasonable or proportionate, nor pursues a legitimate public purpose,” Forst wrote. “Rather, I am gravely concerned that a sanction of this magnitude is purely punitive and repressive.”

That Zoom call was a key piece of evidence for the prosecution case. Made just days before the M25 protests began, the call was, the prosecution said, part of efforts to recruit volunteers to take part in the direct actions. Unbeknown to those taking part, it had been infiltrated by a Sun journalist who recorded it and passed it to the Metropolitan police.

On the face of it, the prosecution evidence seemed damning – and was mostly uncontested by the defendants. But it was only after prosecutors completed their case that events in court began to get really interesting.

The defendants had wanted to mount a defence of reasonable excuse. They proposed inviting expert witnesses such as the geophysicist Bill McGuire, who has written extensively on the implications of climate breakdown, to explain why the urgency of the unfolding environmental crisis warranted their actions. Such defence strategies have worked in some previous cases, with defendants acquitted in the face of apparently conclusive evidence.

But Hehir ruled that the defendants in this case could not present any evidence about the climate to the court, save for the brief statements about their philosophical and political beliefs that ultimately would have no bearing on the verdict.

It was in this context that, as the second week of the trial began, protesters began appearing each morning outside the court, displaying placards saying: “Jurors deserve to hear the whole truth.”

Of the defendants, only Hallam disputed the role the prosecution claimed he played in the conspiracy. He told the court he had merely been asked to “give the case for civil disobedience”.

“I wish to say on oath that I was not involved in this campaign,” he said. However, he went on to argue that even if the jury determined he had played a role in the conspiracy, they should find him and his co-defendants not guilty on the basis they had a reasonable excuse or justification for the actions they took.

In a three-hour address, punctuated by interruptions from an irritated Hehir, Hallam lectured the jury on his interpretation of the law, and why, he claimed, it showed the activists had an excuse for blocking the M25 to raise the alarm about climate breakdown.

Hehir told jurors Hallam’s legal analysis was peppered with mistakes. He repeatedly sent the jury out to admonish Hallam for referencing climate science he had ruled irrelevant to the case. But the judge proved more patient than the defendant seemed to expect. In the end, Hallam told jurors: “I apologise to you if I’m a little bit incoherent, I didn’t actually expect that I was going to get this far.”

He did not get much further. The following morning, the judge brought Hallam’s evidence to an end and, after the defendant refused to answer a cross-examination and then refused to leave the witness box, insisting he was not finished, Hehir called police into the court and had him arrested for contempt.

“Democracy in action, guys! Democracy in action,” Hallam said to watching reporters, as he was dragged into the dock, then down to the cells.

It was the first of many such scenes. Later that same day, Shaw was arrested and taken to the cells in almost identical circumstances, and Hehir sent jurors – who had not witnessed the arrests – home early. “I have never had to order a defendant to be arrested in a courtroom before and I’m very sad to have had to do that not once, but twice today,” the judge said.

On the face of it, Hallam and Shaw’s theatrics looked self-defeating. But the defendants believed they contributed to a victory. The following morning, on agreement, four “facts not in dispute” relating to the climate crisis were read into the court record by Fiona Robertson, second barrister for the crown. They were: that the climate crisis was “an existential threat to humanity”; that global heating above 1.5C would have catastrophic consequences; that in the past 12 months average global temperatures were 1.6C above the pre-industrial baseline; and that in October 2022 the government had opened a new round of oil and gas licensing.

It was a development the defendants and their supporters said amounted to the prosecution conceding the climate crisis was “an existential threat to humanity” – and one that they were to refer to throughout the remaining days of the trial.

Forst was in court to see this. He also witnessed much else. Hallam, bailed the previous day, was dragged out of court again after he began speaking straight to jurors during Lancaster’s evidence. Shortly after, Shaw directly challenged the judge, asking: “Why are you not trying the people causing this crisis?” He too was dragged out. Lancaster was next, for refusing to leave the witness box, and that night, all three were remanded to prison. Gethin had to wait but was also arrested for contempt on both Monday and Tuesday.

By the end of the trial, Whittaker De Abreu, the only one who had not represented herself, was the only defendant left in court.

As a punishment for their “persistent disruption”, Hehir slashed the time given to each defendant from one hour to 20 minutes. He further prohibited any mention of the climate crisis, the legal defences he had disallowed or the principle of jury equity – the idea that jurors can acquit based on their conscience.

As Hallam, Shaw, Lancaster and Gethin gave their speeches from behind the reinforced glass screen of the dock, they each proceeded to flout Hehir’s prohibitions, arguing they had been denied a right to a fair trial.

Hallam told jurors: “It’s blindingly obvious to us here first that you have not been given all the evidence you need. You cannot be sure of our guilt if you are not sure that you have not been given the evidence … we have received no good reason why we are not allowed to tell you what is blindingly obvious, namely what I’m not allowed to speak about. If you are not allowed to hear the blindingly obvious then it’s not a fair trial is it?”

It took just a day’s deliberations for the jury to unanimously find them guilty.

Given the recent history of UK climate protest trials, in which defendants have been sentenced to jail for merely mentioning the words “climate change”, and notwithstanding the dramatic arrests in court, Forst said he was surprised the judge gave them an opportunity to mention climate breakdown at all.

“But the little latitude they had to mention climate change was in the meantime emptied of its very meaning by the fact that, overall, the jury was told to ignore most of it,” he added.

Forst also said he was dismayed by the judge’s decision to refuse the defendants a chance to present more fully their evidence about climate breakdown. “That’s precisely one of the serious concerns I have about what is happening in some courts in the UK. Defendants should be allowed to explain why they have decided to use non-conventional but yet peaceful forms of action, like civil disobedience, when they engage in environmental protest,” he said.

It is not just in the UK that climate defenders are facing persecution, according to Forst, but the problems in this country are particularly acute. Protesters in countries such as France and Germany also faced political opposition – and in some cases, police brutality – but when it came to judicial persecution, the UK was unique, he said.

“[Elsewhere] you see environmental activists who block roads or sporting events being sentenced to a fine, or even sometimes suspended prison sentences for instance,” Forst said. “However, while I don’t have a full picture of what’s happening in every country, the UK is a nightmare for climate activists from this point of view, in the sense that the sentences imposed in other countries are neither that harsh, nor that widespread.

“Facing several years of imprisonment for taking part in a Zoom call – this is something I have not seen anywhere else and it is shockingly disproportionate.”

The nightmare is just beginning for Hallam, Shaw, Lancaster, Gethin and Whittaker De Abreu, who have all been remanded to prison before sentencing next Thursday. Hehir has indicated that they face long sentences.

‘She gave me reports on last night’s date with Paul Simon’

Woody Allen, writer, director, co-star, Annie Hall (1977)

We cast Shelley Duvall as the Rolling Stone reporter in Annie Hall because it’s a flaky character and we wanted someone with a little strangeness, not someone who’d have been better playing a quiet schoolteacher or an accountant. She was odd, charming, wonderful-looking in her way and a very good actress with unique screen charisma.

On set, she did pretty much everything on her own. I had no direction to give her. We’d just start the scene and she would come to it with that natural quirky personality. She said the “Kafkaesque” line just like an average person would. When she spoke, with that voice and intonation and look, she made something happen.

I realised she was exactly what we wanted as soon as we began shooting. Before then, you never know what’s going to resonate. Then, when you see the dailies, you realise how good the actor or actress is. With Shelley, it was clear she was giving that character – only words on the page – a real life.

I never saw her socially, or had any conversations with her other than when she’d tell me what a nice time she had with Paul Simon the night before. They began their relationship on the set, so every day just before we shot she would say: “Oh, last night Paul and I stayed up till dawn talking. He’s so great and he’s so charming and he’s so wonderful.”

I didn’t set them up: I just cast them and then got the report every morning. I guess if a film director could have performed a marriage I’d have married them. I was certainly very happy for them, as they were both terrific, gifted people. I was very proud they met on my movie. As told to Catherine Shoard

‘Full of enchantment’

Daryl Hannah, co-star, Roxanne (1987)

While making Roxanne, I had the great fortune to spend quite a bit of quality time with Shelley Duvall. I had long been an admirer of hers since all of her wonderfully quirky Altman films.

Being around Shelley was like being around a magical being – full of creative ideas and enchantment.

‘We were sprayed by the Epping Forest fire brigade’

Michael Palin, co-star, Time Bandits (1981)

I was very sad to hear the news of Shelley Duvall’s death. I worked with her, briefly, when we played the star-crossed lovers in Time Bandits. We spent some time tied to a tree in Epping Forest being sprayed to within an inch of our lives by the local fire brigade.

She was amazingly patient, and very good company. Her soft voice belied strong beliefs and opinions.

She had a great sense of humour and an innate warmth that made her the sort of person you wanted to stay in touch with. Which we did for a while. So sorry that we’ll not be able to laugh and share memories again.

Scientists are calling on the public to help track how British butterflies are moving north as the climate heats up.

Examining 50 years of data, researchers from the wildlife charity Butterfly Conservation, which runs the annual Big Butterfly Count, have identified a clear northerly shift among many species, including the familiar garden favourites the comma, peacock and holly blue.

This is the result of climate breakdown creating warmer habitats, letting certain breeds grow substantially. The migratory red admiral is one example; typically found in southern England in the summer before migrating to Europe for winter, these winged creatures now reside year-round in the UK. Their populations have also increased threefold.

Meanwhile, the holly blue has been spotted in Scotland. Their numbers have expanded by 34%, reflecting the northerly spread. Distribution has also increased by 36% for the peacock, and 53% for the speckled wood.

Echoing this trend further is the Jersey tiger. Previously only seen in the south-west of England, the day-flying moth was first spotted as far north as London during the 2021 Big Butterfly Count.

Dr Zoë Randle, the senior surveys officer at Butterfly Conservation, said: “We’re also seeing other species which have previously suffered severe declines, such as the comma, recovering, with a huge increase of 94% in where it is found. These highly adaptable species are all able to move into new places as the climate warms, but for habitat-specific species, these trends raise serious red flags.”

For the scotch argus, a butterfly found in damp grasslands in the mountainous regions of Scotland, options are more limited. Since 1979, its distribution has decreased by 20%.

“This butterfly used to be found in northern England,” said Randle. “As our environment has warmed, it has shifted northwards to follow the cooler climates. But how far north can the scotch argus go?”

With a 42% decline since 1979, the gatekeeper is another butterfly that has suffered from habitat loss and global heating. The meadow brown has also dropped 22% in distribution, while green-veined white numbers have reduced by 11%.

For Randle, these figures are concerning: “Food plants can’t move like the butterflies do. Species that rely on particular habitats aren’t able to move as freely. This means that if climate change continues, they could become trapped in isolated fragments of remaining habitat, facing the very real threat of extinction.

“A lot of the time we see these patterns of change in isolation, but we have to remember that all creatures in the habitat are linked, including us humans.”

Butterflies form an integral part of our planet’s ecosystem. They serve as pollinators and are sensitive indicators of environmental change. With up to 80% of Britain’s butterflies already showing signs of depletion in either population number or distribution, observing their patterns and preserving habitats is imperative.

The Big Butterfly Count asks people to spend 15 minutes in a sunny spot this summer and record the number and type of butterflies witnessed. Last year, more than 135,000 counts were conducted across the UK, with volunteers spending a combined time of nearly four years counting butterflies. The information helps scientists understand how the creatures are faring, informs conservation efforts and can shape government policy.

Should I stay or should I go? If I stay there will be trouble … This wasn’t so much a press conference, more a job interview conducted in front of an audience of millions. One where almost everyone had already made up their mind that they would rather almost anyone else got the nod.

This was politics as a bloodsport. Painful to watch. Like intruding on a personal grief. Because there could be no winner here. Were Joe Biden to be word perfect and razor sharp, the doubts would remain about his cognitive abilities. The US president cannot erase his recent past. The gaffes come with ever increasing frequency. The obvious confusion. The long silences. The middle-distance stares.

The tipping point was last month’s presidential debate with Donald Trump. Biden tried to pass it off as one bad moment. The reality was that it was an excruciating 90 minutes. A complete meltdown no pretence or artifice could cover up. You would be embarrassed if this was an elderly relative. No one should be allowed to humiliate themselves in this way. But this was the most powerful man in the western world.

There was no coming back. Senior Democrats have become increasingly vocal about calling for him to step down. Nancy Pelosi has been notably careful in what she says. Congressmen have spoken out. George Clooney – reportedly with the implicit support of Barack Obama – has said it’s time for Biden to go.

But Joe is the only person who can’t read the room. He could step down with dignity. He could point to his record over the last four years and say that at 81 he has had enough. That it’s time for someone else to take over. Yet Biden has dug his heels in and so this can only end one way. With him being dethroned. Either by losing the presidency to Trump or being forced out by increasingly desperate members of his own party.

It’s like a TV show. Imagine a world where Donald Trump – no stranger to getting things wrong and inventing his own reality – is considered to be the model of cognitive competence. But we are where we are. To the rest of the world it’s a sick joke, only one where there are no longer any laughs. We’re way beyond that point now. It’s a theatre of cruelty where the stakes are unbelievably high.

The post-Nato press conference was the first opportunity for the world to see Biden in the raw since the debate. Biden unplugged. Biden unscripted. Sure he could read his opening statement off the autocue but then he would have to take questions from the media. A test of whether he could hold it together for nearly an hour. That’s how low the presidency has sunk. We’re obliged to give a president a free pass on the basis of limited information.

Things didn’t get off to the best of starts. Ninety minutes before he gave his solo press conference he hosted the Ukraine Compact in front of dozens of world leaders. Making the introductions he referred to Volodymyr Zelenskiy as President Putin. And this was off an autocue. He tried to brush it off as a slip of the tongue. A joke even. But the damage was already done. Do that sort of thing once and you can get away with it. Do it repeatedly and people aren’t so forgiving. Especially when most people are primarily listening out for the mistakes.

You could see the awkwardness on everyone’s face. Not long after, Keir Starmer was asked at his own press conference if this was yet another sign of Biden’s mental decline. The prime minister was a model of diplomacy. He had spent much of the conference telling the British media how on the ball the US president had been throughout and he insisted Biden be judged on his performance over the whole two days. He carefully avoided any reference to this latest mistake. But it’s not a good look when world leaders have to cover up.

Just before 7.30pm in Washington, Biden went out to face a hostile media, all of whom were looking for any weakness. The president was no more than a global lab rat. He deserves better than that. He deserves respect for his achievements. But respect cuts both ways. His family should have enough respect for him not to put him through such an ordeal. A quiet word that enough is enough.

We had been warned that he might only take four questions but he went on to take 10. He was on a mission to prove there was nothing wrong with him. That he could take on all comers. Except he couldn’t. There was no coming back from the Zelenskiy/Putin debacle.

The best that could be said about the press conference was that it wasn’t as bad as it might have been. Though that is to damn it with faint praise. There were long moments when Biden was perfectly lucid, with a stronger grasp of foreign policy than Trump could ever have managed.

But equally there were many moments when he appeared confused. His sentences would start nowhere in particular and then abruptly tail off. His delivery was dreamy, disconnected and detached. At one point during a rambling diversion about Finland, he became distracted and fell silent for a moment. You could sense the embarrassment in the room. The media were reluctant participants at the crime scene.

And of course there were the inevitable gaffes. Mistaking Europe for Asia barely rated a mention. Calling Kamala Harris “vice-president Trump” certainly did. That sent shockwaves through the nation. You just can’t go on making those sorts of mistakes and pretend that nothing is the matter. A decline on this scale should never have to be this public.

“I’m ready now and I will be ready three years from now to deal with Putin,” he insisted. Only he didn’t sound like it. Nor did he look like it. It’s as if Biden is waiting on a miracle. To reset his campaign to a Day Zero when none of this has ever happened. Where all mistakes are forgotten. Only it doesn’t work like this. We’ve gone way too far for that.

Nor is it enough merely to respond with the counter-factual of imagining how Donald Trump might have answered any of these questions. The bar shouldn’t have to be this low. The Democrats deserve better. America deserves better. The world deserves better.

California’s wildfire season is off to a ferocious start, with the state’s top wildfire official saying that fires have already burned through five times the average amount of land for this time of year.

Speaking at a news conference on Wednesday, Joe Tyler, the director of the California department of forestry and fire protection (Cal Fire), said the state has responded to more than 3,500 wildfires so far this year. Together, those fires have scorched nearly 220,000 acres – more than five times above what is typical for mid-July, which is considered fairly early in the state’s wildfire season.

“We are not just in a fire season, we are in a fire year,” Tyler said at the news conference. “Our winds and the recent heatwave have exacerbated the issue, consuming thousands of acres. So we need to be extra cautious.”

Authorities across the US west have warned of the rising risk of wildfires amid a protracted heatwave that has dried out the landscape and smashed temperatures records from California to Oregon to Nevada.

“Climate change is real,” said California’s governor, Gavin Newsom, on Wednesday. “Those extremes are here present every day in the great state of California.”

An abundantly wet winter has left landscapes across California coated in grasses that quickly dried as the weather warmed, creating abundant fuel for fast-burning brush fires.

California crews were working in scorching temperatures to battle numerous wildfires on Thursday, including a stubborn 34,000-acre blaze known as the Lake fire, which prompted evacuation orders for about 200 homes in the mountains of Santa Barbara county, north-west of Los Angeles.

In Oregon on Thursday, crews were battling the Larch Creek fire, which has grown to more than 11,000 acres since Tuesday. Lower temperatures and calming winds were helping the crews’ efforts, but the local fire danger level remained extreme. One firefighter was treated for heat-related injuries.

In Hawaii, Haleakala national park on Maui was closed as firefighters battled a blaze on the slopes of a mountain. Visitors in more than 150 vehicles that had gone up on Wednesday for the famous sunset views were not able to descend until about 4am on Thursday because the narrow roads were blocked by fire crews.

More than 63 million people in the US remained under heat alerts on Thursday, as forecasters predicted some relief from the heat was due by the weekend.

Las Vegas set a new record on Wednesday when it saw its record fifth consecutive day of temperatures sizzling at 115F (46.1C) or greater. Already, Nevada’s largest city has broken 16 heat records since 1 June “and we’re not even halfway through July yet”, a National Weather Service meteorologist, Morgan Stessman, said on Wednesday.

That includes an all-time high of 120F set on Sunday, which beat the previous 117F record.

The heat has been suspected in deaths across multiple states. In California, officials in the Silicon Valley county of Santa Clara are investigating 19 potential heat-related deaths, including three homeless individuals, the county’s medical examiner-coroner’s office said in a statement on Thursday. And in Oregon, the number of potentially heat-related deaths has risen to 10, according to the state medical examiner’s office.

Heat was blamed for a motorcyclist’s death last weekend in Death Valley national park and the National Park Service is investigating the third death of a Grand Canyon hiker in recent weeks. Arizona authorities are investigating deaths of a two-year-old and a baby in separate incidents, and in Nebraska, Omaha police say a boy died after being left in an SUV.

Read more on wildfires and heat in the US

Joe Biden has accidentally introduced the Ukrainian president, Volodymyr Zelenskiy, as “President Putin” in a gaffe that will fuel further concerns about his mental acuity that have threatened to scuttle his presidential campaign.

Biden made the mistake while flanked by Nato leaders during a signing ceremony alongside Zelenskiy on the final day of the Nato summit in Washington. It came just an hour before a rare press conference by Biden that has been called “make-or-break” for his campaign, as a growing number of political allies and donors have been calling for him to drop out of the race.

Concluding his opening remarks, Biden handed over to Zelenskiy with the words: “Now I want to hand it over to the president of Ukraine, who has as much courage as he has determination.”

He said: “Ladies and gentlemen, President Putin!”

A number of European leaders began clapping hesitantly. German chancellor Olaf Scholz and Italian prime minister Giorgia Meloni turned their heads in surprise as Biden mentioned the Russian leader, while other European leaders broke into an awkward smattering of applause.

Realising his mistake, Biden caught himself and said: “President Putin! We’re going to beat President Putin. President Zelenskiy. I’m so focused on beating Putin. We’ve got to worry about it. Anyway, Mr President.”

“I’m better,” Zelenskiy said, shaking Biden’s hand.

“You are a hell of a lot better,” Biden responded in concluding his remarks.

The remark elicited gasps in a press centre, where hundreds of journalists were watching the remarks live on an internal television feed. A number of people in the room shouted out “Zelenskiy” to correct Biden’s mistake, after which he returned to the podium.

Zelenskiy had been due to give a press conference at the end of the Nato summit an hour later. But journalists who were waiting were told at short notice that the event was cancelled – meaning he didn’t have to respond to questions about Biden’s gaffe.

The news about the mistake quickly filtered into other press conferences with heads of government, rehashing questions about Biden’s mental state that have loomed over the conference since it began.

Keir Starmer, asked about President Biden’s gaffe, insisted that the Nato summit had made breakthroughs that were welcomed by President Zelenskiy and had left Nato in a stronger position.

Pressed by reporters on whether the US president was capable of serving another four years in office, he said: “Look, I was with him last night. We spent the best part of an hour together. We covered a lot of ground.

“We’ve been through two days of this council and come to a very good outcome. He’s led through all, spoken at every session, pulled people together, and we got a good outcome and I think he should give credit for that.”

French president Emanuel Macron in his press conference said: “Slips of the tongue happen, it’s happened to me.”

Scholz was asked, in English, about Biden’s gaffe in a press conference a few minutes later. He sidestepped the question, and said he hoped that Biden would continue to strongly support Ukraine.

Donald Trump’s running mate will be introduced at the Republican national convention next Wednesday by his eldest son, according to people familiar with the matter, raising speculation that Senator JD Vance will be named the vice-presidential pick after being endorsed by Don Jr.

The fact that Don Jr will speak immediately before the running mate delivers remarks, earlier reported by Axios, is seen as notable inside the Trump campaign because of Don Jr’s close ties to Vance.

Still, a person directly familiar with the matter cautioned that the speaking schedule was decided three to four weeks ago and they were uncertain how instructive Don Jr’s involvement was.

Trump has said he wants his running mate to be revealed at the convention next week in Milwaukee, Wisconsin, but due to convention rules that require the ticket to be nominated by the first day, the former president has been forced to make a decision before Wednesday.

For months, Trump has presided over a characteristically theatrical selection process in which he made dramatic pronouncements at rallies in an effort to drive media speculation before narrowing the list to a final three: the North Dakota governor, Doug Burgum, Senator Marco Rubio and Vance.

The leading contenders have run through an emotionally draining fight to be Trump’s running mate, defending the former president in cable news interviews, mingling with members at Trump’s Mar-a-Lago club, coalescing support from Trump allies and trying to appeal to Trump’s core Maga voters at rallies.

The Guardian has previously reported that Trump has told allies he wants a running mate who would be a “fighter” – someone who is media-savvy and will defend him on adversarial TV networks – and loyal to the extent that they would be “everything Mike Pence wasn’t”.

Trump’s former vice-president was a valuable asset during the 2016 and 2020 campaigns because of his Christian conservative credentials that shored up support among Republicans who were suspicious of the thrice-married reality TV star.

But Pence’s refusal to do one final favor and comply with Trump’s demand to block the certification of the 2020 election results in Congress led to a falling-out, and made Pence the target of the January 6 Capitol attack rioters.

For his 2024 campaign, Trump is seeking a “Goldilocks” running mate: strong but loyal, in tune with Maga but not over-rehearsed, telegenic but not likely to outshine him. His choice will go up against Kamala Harris, the first Black woman to serve as vice-president.

Vance, the junior senator from Ohio, has increasingly fit that profile.

On Sunday, Vance said on NBC’s Meet the Press that he supported Trump’s vow to appoint a special counsel to prosecute Joe Biden, making apparent references to the House oversight committee’s search for evidence of impeachable conduct by Biden, which it has not found.

Vance also suggested it was reasonable for Trump to prosecute Biden on the grounds that Biden had supposedly weaponized the legal system against him, although there is no evidence Biden has been involved in prosecutorial decisions at the justice department or elsewhere.

The NBC anchor Kristen Welker pressed Vance on his support for a special counsel: “If it’s not OK for Joe Biden to weaponize the justice department – as you say, which there’s no evidence of that – why is it OK for Donald Trump to do that?” she asked.

Vance repeated the common complaint among Republicans that one former justice department official took a job as a prosecutor in the New York criminal case in which Trump was convicted of 34 felony counts of falsifying business records to influence the 2016 election with a hush-money scheme.

“If Donald Trump’s attorney general had his No 2 or his No 3 jump ship to a local prosecutor’s office in Ohio or Wisconsin, and that person then went after Donald Trump’s political opposition, that’s a different conversation,” he said, though the prosecutor at issue was not as senior as the hypothetical.

Trump has repeatedly vowed to prosecute his political enemies, sharing posts on his Truth Social website that advocated jailing top Democrats and Republicans who criticized him, including one that said the former House Republican Liz Cheney should face “televised military tribunals”.