Keir Starmer is finished - I just agreed with Diane Abbott for the very first time

In politics these days it seems there are few moments that genuinely shock you. But last night was one of them. After watching news that Sir Keir Starmer had addressed his back benchers - a meeting that reportedly erupted in rapturous applause for the dishevelled-looking Prime Minister - I found myself agreeing with Diane Abbot.

The mother of the house who rose to fame after stating she believed police officers cost about a tuppence stepped in front of the news cameras to suggest what every right-thinking person in the country believed.

"I think that the round of applause in the committee room just now was staged," she said, "just as all those endorsements of the prime minister which appeared within five minutes of each other were staged. I cannot see him lasting beyond May's elections."

Having now watched the interview more times that I care to count, I can safely say I did not hallucinate - and I agree with her. The same Ms Abbot, who backed socialist grandpa Jeremy Corbyn, campaigns for nuclear disarmament, once did an interview where she appeared to support Mao Zedong. At long last, Ms Abbot and I have found common ground.

Here she was, one of a handful of figures on the left of politics opting to speak the plain hoest truth while Sir Keir's Cabinet colleagues frantically posted identical messages of support on social media like synchronized swimmers desperately trying to convince the judges that everything is fine.

It is not fine. Nothing about this is fine.

When asked why she thought Sir Keir would stay until May, Ms Abbott replied: "Because they are going to be catastrophic elections and I think the idea is 'let him stay in there and take responsibility'."

I lament as again she is right. Politicians, most would agree I fear, always act in their own self-interest. And none of them wants to inherit this disaster. Two senior advisers have resigned in two days over the Mandelson scandal, and the Prime Minister's already questionable judgment is in ruins. Yet there he stood, receiving orchestrated applause from colleagues who were already calculating when to wield the knife, they just have yet to decide whose shaking hand it will be pressed.

The timeline is brutally clear. The Gorton and Denton by-election arrives in a few weeks. A safe Labour seat in Manchester that should mean the election is a mere formality. If Sir Keir survives that - and he might, purely because nobody else wants to carry the can for what comes next - then May's local elections loom. They will be, as Ms Abbott predicts, catastrophic.

That is when Labour MPs will strike. Not before, because why take responsibility for inevitable defeat? Let Sir Keir absorb the punishment then let him stand at the despatch box defending the indefensible once more. Let him face the voters' fury and then, once the damage is done, remove him and present the country with a fresh face unburdened by the Mandelson disaster.

It is as cynical as it is calculated. And therefore it is exactly how Westminster works.

The staged applause at last night's meeting was not support, it was theatre. The coordinated social media endorsements from Cabinet Ministers were not genuine loyalty, they were survival instinct. Everyone knows Sir Keir is finished - they are simply positioning themselves for what comes next.

Ms Abbott has spent her long career on the Left of Labour politics. I have spent my (far shorted) career arguing against virtually everything she represents. Yet on this, she has called it perfectly. Sir Keir will not last beyond May. His own party knows it and now they are simply waiting for the right moment to act.

When Diane Abbott and I agree on something, you know the situation is truly dire. Sir Keir's premiership is not merely in trouble. It is already over. His colleagues are just waiting for him to realise it.