"I'll be positioned in this position by 2027," Starmer declared, joking that if the discussion went well, he might welcome the interviewer into Number 10 for a follow-up talk in the coming year.
There is rarely ever break for prime ministers. Just an hour before we sat down, the PM had been speaking with Ukraine's Volodymyr Zelensky and trying to decipher precisely had happened in Venezuela, where his close ally, US President Donald Trump, had just targeted and seized its leader, Nicolás Maduro.
Once the discussion, which was much longer than normal, had concluded, Maduro had been formally accused in New York.
With the year commences, the Prime Minister seems to have had something of a revitalisation. Maybe even just a little downtime with the family at Chequers, the prime minister's country retreat.
This appeared to have resulted in improved morale than at the saggy end of 2025, a dreadful political year for him.
But are he and his allies being unrealistic if they think his fortunes are set to turn around?
The harsh reality for the PM is that many of his colleagues believe he's not very good at his job. Some of them would rather gamble and get him out this year.
However Sir Keir was having none of it when we spoke on Saturday morning.
Multiple times he insisted he'd be "assessed at the poll", maintaining no one would remove his five-year mandate from him – despite the fact that the optimal path of preventing Nigel Farage and Reform UK reaching No 10 might be for Labour to change its leader.
"We are in the fight of our generation and I plan to lead us," he said.
The problem for the prime minister is that he will be scrutinised long before then – in a mega set of elections in May throughout the UK. He attempted to argue, maybe excessively, that they are concerning who runs local authorities, and who runs the devolved administrations in Holyrood or Cardiff – and not a verdict on Westminster.
True – to some extent. But although he may be reluctant to admit it, No 10 will be held accountable by those elections too.
Despite this, Sir Keir suggesting that there were no circumstances under which he would walk away, even if a his colleagues contested his leadership for the job, should those elections be catastrophic for Labour.
He attempted to explain his low poll ratings by saying the public was naturally eager for things to improve. He aimed to convince me, and the public, that 2026 would be distinct.
The economic situation would recover despite rising unemployment, he said, when plans the administration implemented during their initial choppy year began to show results.
His core message is that in 2026 the country will "see an improvement".
The prime minister may have communicated with renewed vitality than I've seen from him for a some time – more relaxed, perhaps, with a longer slot to talk.
But despite facing pressure from many directions for a more decisive strategy, with much more political clarity, more vigour, more speed and more urgency, his explanations were familiar ones.
When he finds himself in such significant political peril, does he need a different script?
No government, and certainly not one that has been unpopular for an extended period, gets everything its as desired.
The Prime Minister's challenges are not only because governing is challenging, but because he and his team have made mistakes, including in the recent past.
The prime minister admitted that he regretted saying he was "delighted" to welcome back the Egyptian-British activist Alaa Abd El Fattah to the UK after an backlash when comments he'd made in the past – including calls for Zionists and police to be killed – came to light.
Starmer blamed "the process" for not realising what the activist had said before – a fancier way of saying not my fault.
And he is courting evident political dangers as the year unfolds. His close relationship with the US president entails a new complication after Trump's strikes on Venezuela.
Based on years of interviewing Sir Keir Starmer, a former human rights lawyer who was against the war in Iraq, over many years, the thought he would be at ease with such action seems implausible.
He asserted he was a "career-long proponent of international law" but the public "just lack the full picture at the moment".
Some wanted him to criticise the action before we spoke. And the government is expected to face further scrutiny to give an definitive view in Parliament in the next few days.
There has also long been simmering tension in the Labour ranks to revisit some of the results of Brexit.
Sir Keir rejects he's heading in that direction, but his new specific commitment to integrate further with the single market – the vast economic European market – will probably elicit protests that he is breaking his pledge never to try to undo the decisions that flowed from Brexit.
A decision to align with more of the single market will delight many on his backbenches, but it is prime ammunition for Reform and the Conservatives to