No Prime Minister in modern times has consistently wanted lower – and some have occasionally wanted higher – public spending than their Chancellors of the Exchequer.

Tony Blair had a three figure majority, and this gave him the platform to announce, during his second term, a tax rise to fund more NHS spending.

Theresa May had none at all which, during her first manifestation as Prime Minister with the spending-friendly Nick Timothy as her guide, helped to soothe the prospect of any clash with her more conventional Chancellor, Phillip Hammond.

We can only think of one post-war Prime Minister who unfailingly wanted higher levels of public spending than some of his Chancellors were willing to provide.

Harold Macmillan got through four Chancellors in six years – a brisk rate of one every eighteen months.  One went voluntarily: Derick Heathcoat-Amory.  Another outlasted Macmillan: Reggie Maudling.

Another resigned (Peter Thorneycroft) and the last was fired (Selwyn Lloyd).  This rapid turnover was driven by Macmillan’s expansionist instincts.

These appear to be have formed by experience – the consequence of his experience as MP for Stockton during the 1930s, during which he saw mass unemployment as a constituency MP.

Thorneycroft quit, together with his ministerial lieutenants Nigel Birch and Enoch Powell, because they were unwilling to settle for a state spending plan supported by the rest of the Cabinet: they had held out for a figure £50 million lower.

This was not a large proportion of public spending even during the late 1950s, but the three men insisted that it was the principle that counted: in their view, Macmillan was taking risks with inflation.  He dismissed their resignations as “a little local difficulty”.

Selwyn Lloyd was fired partly because he had lost support within the Cabinet, but largely because his instincts were less expansionary than Macmillan’s own.

The latter wanted a less hidebound Chancellor, and duly found one in Reggie Maudling.  “Good luck, old cock!” Maudling wrote two years later in a private note for his Labour successor, Jim Callaghan. “Sorry to leave it in such a mess.”

If Macmillan became a Keynesian by experience, Boris Johnson is a boosterist by instinct.  Like a theatrical impresario, he wants lights, music and action – for which, read tax cuts, grands projets and higher spending.

And like Macmillan, he has already had a Chancellor quit on him, though the cause was process rather than policy.  Rightly or wrongly, Johnson and Dominic Cummings wanted Number Ten and the Treasury joined at the hip, or rather at the top.

Up with this amalgamation, and the consequent sacking of his main advisers, Sajid Javid would not put.  His own later shadow budget, so to speak, produced for the Centre for Policy Studies, was in broad outline much like Rishi Sunak’s real and recent one.

Essentially, both men wanted to spend now and save later.  Or, rather, spend then: the Chancellor’s last Budget was produced during lockdown – on March 3, a few days before the first stage of lockdown easing, the return of children to school on March 8.

But now that we are returning to more normal times and the winter of lockdown is melting away, the unavoidable choices about tax and spending are looming into view.

The Prime Minister’s threat to move Sunak, made in front of a large group of aides – big enough to leak swiftly – wasn’t caused by tensions over economic policy.

Rather, it was by the leaking of a letter from the Chancellor to him urging the faster loosening of travel restrictions.  Nor should Johnson going “f***ing tonto”, as one of those at the meeting apparently put it, be taken too seriously.

It is part of the Prime Minister’s modus operandi to let off steam, and disperse words and ideas like chaff, in order to find out what he thinks.  His motto is Auden’s: “how do I know what I think until I see what I say?”

So read the counter-briefing by anoymous “friends” of Sunak’s – to the effect that the Chancellor would rather quit than accept demotion – with a cool head amidst the summer lightning.  This is the silly season, after all, and this silliness must be kept in proportion.

All the same, we have a boosterist Prime Minister, whose instinct for higher spending sits well with more state-reliant constituencies, like a mass of those that the Conservatives won at the last election in the provincial north and midlands.

And a more conventional Chancellor, who has warned that spending, deficits and debt must be kept under control.  Is Sunak a Thorneycroft, ready to resign on principle?  Or has Javid already played that part?

Or is the Chancellor a Selwyn Lloyd, to be ousted in some Johnsonian “night of the long knives” – the phrase originally applied to the shuffle in which Selwyn Lloyd was one of seven Cabinet Ministers fired?

Or is he neither?  Probably the last.  All the same, when Prime Ministers eye the control panel of the spending aircraft, Chancellors tug nervously at their parachutes and check the exit doors.