"I will remain in the same office by 2027," the Prime Minister declared, adding that if our discussion went well, he might invite the interviewer into Number 10 for another talk in 2026.
For a PM, there's never any break for those in the top job. In the hour before we sat down, Starmer had been in calls with Ukrainian President Volodymyr Zelensky and trying to work out exactly what had happened in Venezuela, where his close friend, US President Donald Trump, had just targeted and seized its leader, Nicolás Maduro.
Once the discussion, which was far more extended than typical, had finished, Maduro had been charged in New York.
With the year starts, Sir Keir appears to have had a kind of a revitalisation. Maybe even just some relaxation with his family at Chequers, the prime minister's official country residence.
This appeared to have resulted in improved morale than at the saggy tail end of 2025, a dreadful year politically for him.
Yet, are he and his colleagues kidding themselves if they think his fortunes are set to get better?
The grisly truth for the leader is that many of his party members think he's underperforming at his job. Some of them would rather take a risk and get him out sooner rather than later.
But Starmer was dismissing such talk during our conversation on Saturday morning.
Multiple times he told me he'd be "judged at the next election", arguing no one would remove his five-year mandate from him – despite the fact that the optimal path of halting Nigel Farage and Reform UK entering No 10 may be for Labour to switch leader.
"We are in the fight of our generation and I aim to guide the party," he affirmed.
The challenge for the prime minister is that he will be judged well ahead of then – in a huge set of elections in May throughout the UK. He sought to argue, maybe excessively, that they are about who runs councils, and who runs the devolved administrations in Holyrood or Cardiff – and unrelated to Westminster.
Accurate – in part. But even though he may be reluctant to concede it, No 10 will be judged by those elections too.
This did not stop Sir Keir stating that there were no situation under which he would step down, should a his MPs challenged him for the job, if those elections prove very poor for Labour.
He attempted to rationalise his unpopularity by saying the voters was naturally impatient for things to get better. He aimed to persuade me, and the public, that 2026 would be distinct.
The economy would strengthen notwithstanding rising unemployment, he argued, when plans the administration enacted during their initial choppy year began to bear fruit.
His big argument is that this year the country will "reach a turning point".
The prime minister may have communicated with renewed vitality than observed from him for a some time – less tense, perhaps, with more time to talk.
However, in spite of facing calls from various quarters for a bolder strategy, with much more political clarity, more vigour, more speed and more immediacy, his explanations were familiar ones.
Given that he is in this much political difficulty, is a different approach required a different script?
No government, and certainly not one that has been unpopular for an extended period, gets everything its own way.
Sir Keir's challenges are not just because governing is difficult, but because he and his team have faltered, including in the last few weeks.
The prime minister admitted that he was sorry for saying he was "pleased" to see the return of the Egyptian-British activist Alaa Abd El Fattah to the UK after an backlash when comments he'd previously made – such as calls for Zionists and police to be killed – resurfaced.
Sir Keir attributed it to "the system" for not catching what the activist had said before – a fancier way of saying not my fault.
And he is inviting evident political dangers as the year progresses. His close relationship with the US president takes on a new complication after Trump's strikes on Venezuela.
Based on years of interviewing Sir Keir Starmer, a former human rights lawyer who opposed the war in Iraq, over his career, the thought he would be comfortable with these events seems unlikely.
He told me he was a "career-long champion of international law" but we "simply lack the entire story at the moment".
Critics called for him to denounce it before we spoke. And the government is likely to face increased demands to give an clear view in Parliament in the near future.
And there has long been simmering tension in the Labour party to revisit some of the results of Brexit.
Sir Keir denies he's heading in that direction, but his new firmer pledge to move closer with the EU's single market – the giant economic European trading zone – will likely elicit howls that he is reneging on his pledge never to try to undo the results that followed Brexit.
A commitment to cosy up to more of the single market will delight many on his backbenches, but it is easy fodder for Reform and the Conservatives to