Mr Starmer goes to Washington: how the PM made his world stage entrance | Keir Starmer

As Keir Starmer arrived at the Oval Office, Joe Biden was at the door to meet him. “Come on in, man,” the US president told him. The invitation was not simply to enter the heart of the White House, but also the major league of world leaders.

The day before, on the flight to Washington DC for the Nato summit on Tuesday, Starmer admitted that the days since the Labour party had pulled off its landslide election victory had been a bit of a whirlwind.

“This time last week … I was just checking into a hotel that was more like a bed and breakfast in Carmarthen and about to do the last day of the campaign. And here we are now on the way to the Nato summit – so a real transition,” he said.

Biden was a generous host. The White House, not usually keen on bilateral talks during major international summits so as to avoid any individual nation feeling left out, made an exception for the newly elected Starmer.

Sitting alongside the prime minister under a portrait of Franklin D Roosevelt, Biden told reporters that the two countries were the “best of allies in the whole world”, before their timetabled 45-minute meeting stretched to almost an hour.

For Starmer, the visit could not have come at a better time. Just five days into office, and with a massive parliamentary majority of 174 under his belt, other leaders wanted to find out how he had done it, especially those facing political headwinds at home. “Everybody loves a winner,” said one official.

Over the course of two days in DC, Starmer and his team of David Lammy, the foreign secretary, and John Healey, the defence secretary, managed between them to meet every one of the other 31 Nato leaders.

They included natural allies – progressives such as Justin Trudeau of Canada and Olaf Scholz of Germany – but also those less likely to be regarded as natural political bedfellows, such as Italy’s Georgia Meloni and Viktor Orbán, the Hungarian prime minister who put Nato backs up by meeting Vladimir Putin and Donald Trump within the space of a week.

“Labour is looking to reset that and encourage more, even though there’s a difference of political views,” Healey said after a brief meeting with Orbán.

As well as striking personal relationships – Starmer’s preferred method of diplomacy – the summit also gave the prime minister the opportunity to show off his national security credentials to a domestic and international audience.

“It’s a good early opportunity for me to set out my priorities, to obviously engage with other international leaders,” he said in a television interview midway through the summit.

“To have that within the first two weeks or so of an incoming Labour government is a really good opportunity to address core values … about the commitment to Nato, the importance of the defence on Ukraine. And with my bilateral with the president of the US here yesterday, to be very clear about the nature and importance of the special relationship between our two countries.”

At Starmer’s side was his wife, Victoria, who despite opting not to have a high-profile public role herself, was there to support her husband at his first international summit.

Her brief public appearances – wearing a £450 cream, lace-knit dress from the British label Needle & Thread as she walked down the plane steps at Andrews air force base, and in a £329 tomato red dress from the French company The Kooples for a White House welcome dinner – added some glamour.

But she also brought a human touch to an otherwise formal event: Starmer credits his wife and children for keeping him grounded. Aides said she hit it off, in particular, with Olena Zelenska, the Ukrainian president’s wife.

At the glitzy White House dinner, guests were treated to a dinner of charcoal-grilled beef tenderloin and Alaskan halibut – although presumably not the vegetarian Starmers – and a military fly-past which they watched from the balcony, Victoria’s arm draped around her husband’s shoulder.

Starmer once again proved himself to be a lucky general, with England qualifying for the Euro 2024 final during the summit, creating a feelgood factor at home that Downing Street will hope continues.

The prime minister, a passionate football fan, revealed that he stepped out of meetings to watch part of the semi-final with the Dutch prime minister, Dick Schoof, and caught Harry Kane scoring England’s first goal. He missed the second, but aides suggested he would watch it when he got home.

Even Biden got in on the act, shaking Starmer’s hand in the Oval Office and declaring: “England. In the finals! I’ll tell you what – it’s all because of the prime minister.” Starmer laughed coyly and blushed.

Despite the apparent success of Starmer’s arrival on the world stage, he did not manage to escape the challenges waiting for him back home entirely. As the scale of the prisons overcrowding crisis became clear, he was asked questions at every turn about how he would handle it.

The prime minister also came under pressure over his commitment to defence, after he repeatedly refused to put a date on raising spending to 2.5% of GDP. Yet despite not setting out his own timetable, he said it was “essential” for Nato countries to match that target.

The biggest cloud over the heavy Washington sky was Biden’s future. After the Oval Office talks, Starmer said he was “on good form” and had gone through serious issues “at pace”. Aides in the room backed up his account, suggesting Biden had navigated the knotty details of foreign policy while also being quick-witted enough to make jokes.

But the US president’s gaffe at the closing Nato press conference – introducing Volodymyr Zelenskiy as “President Putin” – fuelled yet more of the concerns about his mental acuity that have threatened to scuttle his presidential campaign.

At Starmer’s own closing press conference, he was asked repeatedly for his views. He said little other than that the US president “deserved credit” for the overall success of the summit, which he said had left the alliance stronger than ever.

But he is aware that the drama will overshadow what Downing Street regarded as a successful first international trip, and that after Sunday’s final, public attention in England will refocus on the many domestic challenges ahead.

Starmer, who has blamed the inheritance from the Tories for tough choices he will have to make, said he hoped people would be patient. “We can get started, roll up our sleeves and hit the ground running,” he said. “But real long-term fixes will take time.”