Thursday was a bad day at the office for Sir Keir Starmer. The Prime Minister is already fighting fires on several fronts: the forthcoming Makerfield by-election, which is likely to return Andy Burnham to the House of Commons; an outbreak of anti-immigrant mob violence in Northern Ireland; the cost of living rising due to the ongoing US/Israel/Iran conflict; the continuing toxic fallout from Starmer’s appointment of Lord Mandelson as British Ambassador to the United States.

Starmer has been under sustained fire over the grotesquely late Defence Investment Plan (DIP) and the level of additional public expenditure on defence it contains for some time. The government has not been taking defence spending seriously enough and seemed to be turning a blind eye to the weaknesses with which the armed forces are riddled. A three-way struggle between the Ministry of Defence, HM Treasury and 10 Downing Street has been going on since at least December last year.

The core of the problem is that most people accept that Healey’s critique is correct

Something had to give, and on Thursday it did. John Healey, Secretary of State for Defence, resigned, writing to the Prime Minister to explain why in quietly devastating terms. Healey had seen the final financial settlement of the DIP on Monday, and it is clear he simply could not live with it: