"I'll be positioned in this seat by 2027," the Prime Minister declared, noting that if the conversation proceeded smoothly, he might invite us into his official residence for a follow-up talk next year.
There is never truly downtime for prime ministers. Just an hour before we sat down, the PM had been speaking with Ukraine's Volodymyr Zelensky and trying to work out what on earth had happened in Venezuela, where his close friend, US President Donald Trump, had just attacked and captured its leader, Nicolás Maduro.
Once our interview, which was far more extended than usual, had concluded, Maduro had been indicted in New York.
With the year commences, the Prime Minister seems to have had a degree of a refresh. Maybe even just some downtime with his family at Chequers, the prime minister's official country residence.
That certainly appeared to have left him in improved morale than at the saggy end of 2025, a terrible annus horribilis for him.
But are he and his allies kidding themselves if they believe his fortunes are set to improve?
The grisly reality for the PM is that many of his colleagues are convinced he's underperforming at his job. A faction of them would rather take a risk and oust him this year.
However Sir Keir was rejecting the idea when we spoke on Saturday morning.
On several occasions he told me he'd be "assessed at the next election", arguing no one would strip his electoral mandate from him – even if the most effective strategy of stopping Nigel Farage and Reform UK entering No 10 may be for Labour to switch its leader.
"This is the struggle of our times and I plan to guide the party," he affirmed.
The problem for the PM is that he will be judged well ahead of then – in a mega set of elections in May across the UK. He sought to protest, perhaps excessively, that they are about who runs councils, and who runs the governments in Holyrood or Cardiff – and not a verdict on Westminster.
True – up to a point. But although he may not want to admit it, No 10 will be held accountable by those elections too.
This did not stop Sir Keir implying that there were no circumstances under which he would resign, should a his MPs contested his leadership for the job, if those elections prove catastrophic for Labour.
He tried to rationalise his low poll ratings by saying the voters was naturally impatient for things to change. He tried to convince me, and the nation, that the coming months would be a change.
The economy would improve in the face of rising unemployment, he claimed, when plans the government enacted during their first rocky year began to bear fruit.
His central point is that this year the country will "see an improvement".
The prime minister may have spoken with more energy than I've seen from him for a while – calmer, maybe, with a longer slot to talk.
However, in spite of encountering demands from various quarters for a bolder strategy, with much more political direction, more vigour, more speed and more immediacy, his arguments were familiar ones.
When he finds himself in this much political trouble, should he consider a new narrative?
No government, and especially not one that has been struggling in the polls for many months, has everything its as planned.
The Prime Minister's challenges are not only because government is challenging, but because he and his colleagues have faltered, even in the recent past.
The prime minister expressed regret that he was sorry for saying he was "pleased" to welcome back the Egyptian-British activist Alaa Abd El Fattah to the UK after an backlash when statements he'd previously made – such as calls for Zionists and police to be killed – came to light.
Sir Keir attributed it to "procedures" for not realising what the activist had said before – a more diplomatic way of saying not my fault.
And he is inviting clear political risks as the year progresses. His close relationship with the US president takes on a new risk after Trump's military action on Venezuela.
Having interviewed Sir Keir Starmer, a former human rights lawyer who was against the war in Iraq, over his career, the notion he would be at ease with this kind of intervention seems far-fetched.
He told me he was a "longtime proponent of international law" but the public "just lack the complete details at the moment".
Critics wanted him to criticise the action before we spoke. And the government is expected to face further scrutiny to give an explicit view in Parliament in the next few days.
And there has always been simmering pressure in the Labour ranks to undo or remake some of the results of Brexit.
Sir Keir disputes he's doing that, but his new more concrete plan to integrate further with the EU's single market – the giant economic European trading zone – will probably provoke howls that he is reneging on his pledge never to try to undo the choices that stemmed from Brexit.
A decision to align with more of the single market will satisfy some on his side of the party, but it is prime ammunition for Reform and the Conservatives to
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