Chris Mason: The anatomy of Prime Minister Sir Keir Starmer's downfall

But there were parallels with the downfall of both Johnson and Truss: Sir Keir, like both of them, had lost the capacity to viably govern. When that happens to a prime minister, they are done for. Theories abound about why our last five prime ministers have not lasted very long. To what extent is a stagnant economic picture, dating back to the financial crisis of nearly 20 years ago to blame? What about the incessant noise of social media? In the midst of it all, Morgan McSweeney , the man who had been at Sir Keir's side for his entire time in political leadership, both in opposition and government, resigned, as did yet another No 10 director of communications, Tim Allan. It is our job as journalists to chronicle this to the best of our ability, and so give you a real sense of what is really going on, often a long way from TV cameras and microphones. By necessity, much of this is off the record – information and sentiments shared with us, on the condition we don't reveal publicly who it is we have spoken to in a way that could identify them. Like in any organisation, or indeed family, sometimes the most candid views are expressed privately, at least up to the point that the weight of an opinion becomes sufficiently significant that people choose to share their view more widely. This story came to light because the prime minister's allies were fearful he faced imminent danger. They were sufficiently fearful that they were willing to advertise their own vulnerability in the hope of diminishing the likelihood of him facing a challenge. By New Year's Eve, these private conversations meant I could report 2026 would be Sir Keir's make or break year, and the likely fulcrum of the political year would be the elections in May. It was clear then, as we reported at the time, that this was unlikely to be the end of the matter – and so it proved. The elections in May solidified in the minds of countless MPs what many of them had long feared - their leader was deeply, deeply unpopular and costing their party support. The view of Labour MPs, channelling what they saw as the view of the electorate, calcified to a point where Sir Keir's imminent departure became near inevitable. Against that backdrop, he was powerless to prevent Andy Burnham contesting the by-election triggered in Makerfield in Greater Manchester to give him a chance to return to Westminster and take over as Labour leader. Now, at the end of a week in which the prime minister has set out a timetable for his departure and a newly re-elected Andy Burnham assembles a programme for government, we witness what remains of Sir Keir's government disintegrating before our eyes. Andy Burnham will give a set-piece speech at the beginning of next week sketching out some of his planned key themes and by the middle of next month he is highly likely to be prime minister.