If many more billions are to be spent on defence, where will the money come from?

Once under the spell of Admirals and Generals, they become zealous in the cause of defence spending, above and beyond other considerations.

Whereas the Tories and the top brass went to the same schools and meet in the same clubs, Labour ministers have sometimes felt a requirement to demonstrate that they are not closet pinkos, reluctant to fight the patriotic corner.

Therein lies a paradox of our times. If the UK’s defence capability has been “hollowed out” as alleged, it has not been by Keir Starmer or the Labour government. The Tories held power for 18 years and, as on so many fronts, left a dismal legacy. Two years is not a long time in politics or defence spending.

John Healey would doubtless deny having gone excessively native within the MoD. But his dramatic departure and the dagger aimed at the government of which he was part does strike me as politically perverse and unreasonably disloyal.

This is all the more true because of the lengthy preamble in which Mr Healey’s resignation letter lists the government’s achievements in the defence sphere over these two years. By any government standard, it is formidable, including a rise in defence investment to 2.5 per cent of GDP “three years earlier than anyone expected”; launching “the deepest defence reforms in 50 years” and giving the Armed Forces “the biggest pay rise in 20 years”.

Yet Mr Healey has walked out over a struggle with the Treasury about how many additional billions can be committed to the Defence Investment Plan “to defend the country at this time of rising threats”. Maybe he should have stayed to fight his corner, rather than poison the chalice for any successor.

There has been no shortage of Tory MPs, retired military men and other regulars on the media circuit eager to laud the courage and principle which Mr Healey has displayed or contrast it with how hopeless the Prime Minister has been.

Through the reigns of Cameron, Johnson, May, Truss and Sunak, the same doom-mongers who turn up on every channel to endorse the demand for undefined billions were remarkably restrained in their patriotic forebodings. Now Messrs Healey and Carns have handed them their script on a plate. History before 2024 does not exist.

Other imperatives are not the business of those who – like Mr Healey - use “defence of the realm” as a trump card, if you’ll pardon the expression. Yet the reality facing any government is that each additional billion spent on defence is a billion that will not be spent elsewhere. The NHS? Education? Welfare ….? There is minimal evidence that his Labour colleagues or the voters they represent are prepared to make these sacrifices in the interests of preparing for war.

The most obvious candidate is welfare but when that was put to the test by Starmer, it was roundly rejected by his own backbench MPs, among whom Mr Healey now sits.

He was part of the Cabinet which felt obliged to accept that outcome and is well qualified to understand the challenges faced by those who still sit around the same table – and for whom he has just made life significantly more difficult. I wonder how often Mr Healey took on the same argument at meetings of the Parliamentary Labour Party?

The position of the departed Arms Forces Minister, the Aberdeen-born Everest conqueror, Al Carns, is even more curious. By dint of his distinguished military career, Mr Carns went straight into government in the Ministry of Defence after being elected in 2024. Before that, he had been an adviser to three Tory Defence Secretaries.

Mr Carns now informs us that we are not only spending too little but that we are preparing for the wrong war, which seems pretty fundamental. “While I had no hand in the Defence Investment Plan”, he wrote in his resignation letter, “that distance does allow me to say plainly that it is not built for the threat we face. It is neither transformative enough nor sufficiently funded”.

One can only wonder what advice he used to give to the Tories.

Inadvertently, Mr Carns points to why a world-weary Treasury will always be sceptical about the Ministry of Defence’s spending demands. It has heard them all before and no matter how much is available, it will never be enough and the objectives are not even agreed upon. At the same time, there is an epic reputation for waste.

So someone has to draw the line between what is demanded and what is affordable. That has been a battle within Whitehall since time immemorial. It is difficult to see how it will be advanced by resignations from a government which, whatever its inadequacies, is certainly doing a lot more with far greater intent than the one it replaced, to keep the country safe.

Starmer’s enemies crow that it is another nail in his Prime Ministerial coffin. We’ll see what roles the resignees have in mind for themselves if a leadership content ensues. No matter who is Prime Minister, the same question will remain – if many more billions are to be spent on defence, where will the money come from?

So if Messrs Healey and Carns now have time on their hands, maybe it could be devoted to alerting the citizenry to impending dangers and the sacrifices needed to counter them.

Unless that battle for hearts and minds is won, any government or Defence Secretary will have to live in an imperfect political world where the conspicuous demands of the present vie with less tangible demands of the future. Persuasion might be a more effective weapon than resignations.