"I will be sitting in the same office by 2027," the Prime Minister declared, adding that if our interview went well, he might welcome the interviewer into Number 10 for another chat in the coming year.
There is rarely ever break for prime ministers. Just an hour before we sat down, Starmer had been on the phone with Ukrainian President Volodymyr Zelensky and attempting to work out what on earth had occurred in Venezuela, where his big ally, US President Donald Trump, had recently launched a strike against and detained its leader, Nicolás Maduro.
Once the discussion, which was far more extended than normal, had concluded, Maduro had been formally accused in New York.
But as the new year begins, Sir Keir seems to have had a degree of a revitalisation. Maybe even just some a rest with the family at Chequers, the prime minister's country retreat.
That certainly seemed to have resulted in a more positive mood than at the sluggish conclusion of 2025, a awful political year for him.
But are he and his colleagues kidding themselves if they think his standing are about to improve?
The grisly reality for the leader is that many of his party members are convinced he's ineffective at his job. Some of them would sooner gamble and get him out in 2026.
But Starmer was rejecting the idea during our conversation on Saturday morning.
Repeatedly he insisted he'd be "judged at the general election", insisting nobody would remove his electoral mandate from him – despite the fact that the optimal path of stopping Nigel Farage and Reform UK entering No 10 may be for Labour to change its leader.
"We are in the fight of our times and I aim to lead us," he declared.
The problem for the PM is that he will be assessed well ahead of then – in a huge set of elections in May throughout the UK. He attempted to contend, maybe excessively, that they are concerning who runs councils, and who runs the devolved administrations in Holyrood or Cardiff – and not about Westminster.
True – to some extent. But even though he may be reluctant to acknowledge it, No 10 will be evaluated by those elections too.
This did not stop Sir Keir stating that there were no circumstances under which he would walk away, should one of his colleagues contested his leadership for the job, should those elections prove catastrophic for Labour.
He sought to account for his unpopularity by saying the voters was reasonably anxious for things to improve. He sought to persuade me, and the public, that 2026 would be distinct.
The economic situation would strengthen despite rising unemployment, he said, when strategies the government implemented during their initial turbulent year began to take effect.
His big message is that this year the country will "see an improvement".
The PM may have spoken with renewed vitality than observed from him for a some time – more relaxed, maybe, with more time to talk.
But despite facing calls from various quarters for a bolder approach, with increased political vision, more vigour, more speed and more urgency, his arguments were repeated ones.
Given that he is in this much political peril, is a different approach required a change of tack?
No government, and especially not one that has been unpopular for an extended period, gets everything its as planned.
Sir Keir's challenges are not just because governing is difficult, but because he and his colleagues have erred, including in the last few weeks.
The PM admitted that he was sorry for saying he was "happy" to see the return of the Egyptian-British activist Alaa Abd El Fattah to the UK after an outcry when comments he'd previously made – including calls for Zionists and police to be killed – came to light.
Starmer attributed it to "the process" for not realising what the activist had said before – a more diplomatic way of saying not my fault.
And he is facing evident political dangers as the year unfolds. His friendship with the US president takes on a new risk after Trump's intervention on Venezuela.
Having interviewed Sir Keir Starmer, a ex- human rights lawyer who opposed the war in Iraq, over many years, the idea he would be comfortable with this kind of intervention seems far-fetched.
He told me he was a "longtime proponent of international law" but we "simply lack the complete details at the moment".
Some called for him to criticise the action prior to we spoke. And the administration is likely to face increased demands to give an clear view in Parliament in the next few days.
And there has consistently been growing pressure in the Labour party to undo or remake some of the results of Brexit.
The PM rejects he's heading in that direction, but his new firmer commitment to move closer with the single market – the giant economic European trading zone – will likely elicit protests that he is going back on his promise never to try to reverse the decisions that stemmed from Brexit.
A commitment to align with more of the single market will please some on his backbenches, but it is easy fodder for Reform and the Conservatives to