Health and social care is one of the Government’s two main spending pressure points.  We won’t rehash yesterday’s Cabinet assault on Boris Johnson after he forced a discussion.  Instead, let’s turn to the other bubbling policy and budgetary debate: defence.

The Foreign Secretary may not have got his way yesterday, but another member of Theresa May’s top team did – elsewhere.  At a meeting of the National Security Council, Gavin Williamson won himself more time.  A defence and security review was due to take place in the spring.  The Defence Secretary has succeeded in decoupling the defence element.  The review into it will now report later.  Both Downing Street and the Ministry of Defence will want the whole thing done and dusted before the NATO summit in July.

You may ask why another review is taking place only three years since the last one.  The long and short of it is that the financial compromises reached at the same time have broken down.  There is a black hole in the defence budget of up to £30 billion.  Williamson was presented with three options for cuts.  He rejected all of them.  The Treasury will argue that the MOD must live within its means. And the familiar debate about the costs of defence will recommence.  Like health and social services, these have their own distinctive features: the cost of equipment, the complex procurement budget, MOD staff.  (There is a push to cut civilian staff.)

However, there is more at stake than numbers.  Senior servicemen invariably warn that budgetary pressures are compromising our national security – that the army is too small; that the navy’s carrier programme needs more resourcing; that the new focus on cyber must not be allowed to squeeze conventional defence.  But there seems to be real agitation beneath the usual lobbying.  The head of the army is out and about.  The Defence Select Committee wants defence spending to rise to three per cent of GDP.  Mark Francois, a former Defence Minister, has taken aim in the Commons at the “pin-striped warriors of the Treasury”.  Johnny Mercer has indicated that up to 50 Tory MPs are of similar mind.

A nightmare for each Defence Secretary is that the music will stop on his watch: that it will become impossible to meet the Treasury’s demands for savings by simply postponing new spending decisions and that, somehow or other, a strategic review will recommend choosing between what you might call a European Strategy and a Global Strategy.  The former would concentrate on conventional defence in Europe, as Russia continues to modernise its forces.  The latter would project British power beyond the continent, in keeping with the country’s maritime traditions.  This well-worn debate is more than a bit out of date.  The Islamist security problem at home, as well as abroad, has added a new dimension.  Cyber means new potential security threats from other non-state as well as state actors.

And then there is Brexit.  Leaving the EU both complicates our position abroad and refocuses the defence debate.  It complicates it in that any reverse for Britain is seen as a consequence of the referendum vote, whether it is or not.  Consider the case of how we recently lost our place on the International Court of Justice.  That France failed to get its candidate on to the International Law Commission last year was all but forgotten in the rush to blame Brexit.  If governments abroad and international institutions believe that we are withdrawing from the world, then they’ll believe it – no matter how many times the Prime Minister proclaims “Global Britain”.  EU withdrawal means that we have prove all the more vividly than we intend to stay globally engaged.

There are means of pushing the spending figures about.  David Cameron and George Osborne lumped Trident into the broader defence budget.  This was a means of squeezing defence costs at a time of retrenchment.  It could be given it a separate budget again.  Mike Penning, another former Defence Minister, made the case for change recently.  Then there is DfID.  A common sense view is that Hurricane Irma, say, was an exercise in overseas aid.  It follows that in a rational world DfID would meet at least some of the costs.  But aid rules set internationally prevented it from doing so.  No wonder last summer’s Conservative Manifesto pledged to seek change. No doubt the defence review, when it comes, will seek overall to muddle through.

None the less, the choice cannot be put off forever.  In the crudest possible terms, we must either cut what we do or fund it properly.  The case for the latter would be very strong now even were we not leaving the EU.  But the change is decisive.  We cannot withdraw from the defence of our neighbours, or skimp on it, while proclaiming our commitment to uphold their security.  And we cannot proclaim Global Britain while at the same time reducing our global reach.  The MOD says that the commitment which Lewis is seeking would find it another £18 billion.  (As coincidence would have it, Johnson’s £350 million a week comes in at about £17 billion a year.)

Williamson’s position is in some ways easier than that of the Foreign Secretary or Jeremy Hunt.  True, he came to Defence as a neophyte – and the post is a prized appointment for Tory politicians, outranked in their eyes only by the great offices of state.  His term as Chief Whip made him enemies as well as friends, and his translation to Defence was not universally popular.  So must therefore tussle with the Treasury all the more vigorously to prove that he is up to the job.

Neither he nor Philip Hammond were well-served by ugly early rows between them.  There will be more.  His style is very different from Michael Fallon’s.  Where his predecessor lobbied behind the scenes, Williamson is out making headlines – on army veterans, army dogs.

Some in the MOD may not approve of the change.  But at least the Defence Secretary is Doing Something.  He deserves support in his struggle for adequate funding.  Give the composition of the Parliamentary Party he is certain to get it.