On a political earthquake Richter scale rating of resignations the shock resignation of John Healey as defence secretary is the sort of event which would bring tall buildings with dodgy foundations crashing to the ground.
Mr Healey may not be one of the headline names in the Cabinet but he is highly respected and will always be a Labour loyalist first and foremost. This is not a man who makes a habit of rocking the boat.
So the fact that he has now lost confidence in Sir Keir Starmer’s government, joining the almost 100 Labour MPs who have already publicly declared that, is a sign that this really is over for the prime minister.
He will find a replacement as defence secretary soon enough but we are now counting days rather than weeks or months before the real axe falls.
Essentially, the problem highlighted by Mr Healey in the issue of failing to live up to promises on defence spending is of a government that is dead on its feet. It is barely functioning as a decision making body and is in a state of stasis waiting to see if Greater Manchester mayor Andy Burnham wins the Makerfield by-election and comes back to Westminster where he hopes to take over as Labour leader and prime minister.
A zombie government with so little life that the prime minister has now given up taking questions after a major speech – as happened at London Tech Week on Monday with his speech.
He has a deputy prime minister, David Lammy, who does not want to do press conferences in front of the camera.
The bigger problem is that this is a government unable to make big decisions or stick by them. That has been true since Sir Keir was unable to get his welfare reforms past Labour MPs.
It should be noted that Mr Healey has been discussed as a potential leadership contender, as a continuity candidate.
But it seems unlikely that his resignation is about personal ambitions – it is more borne out of frustration at a government that is unable to see through its commitments.
The pledge of raising defence spending to 3.5 per cent of Gross Domestic Product is not just a matter of political trust but one which is increasingly necessary in a world becoming increasingly fraught by conflict.
A classic sign of weak governments which have lost their way is when the Treasury is able to bully them out of their commitments.
Sir Keir has had the Defence Investment Plan (Dip) sat on his desk for months, while chancellor Rachel Reeves and the Treasury argued with Mr Healey and the Ministry of Defence. He was unable to make a decision. Now it has cost him a loyalist minister.
But the wider issue is more damaging. Sir Keir’s premiership is now mired in frustration. We saw it from the furious reaction by Labour MPs to the local government elections bloodbath last month.
We also saw similar anger in the resignation letters of Wes Streeting as health secretary and Jess Phillips from the Home Office.
This is increasingly becoming a premiership with a prime minister who talks up his plans and then cannot deliver on them.
In the end, if he is forced out in the coming weeks, as most expect, then it will be that frustration and inability to lead and govern which will have been his undoing.