Has Boris Johnson made the first major error of his premiership? Choosing his adviser over his Chancellor could be seen as a bold gamble of the sort that won him a sweeping election victory and got the UK out of the European Union. We of little faith in the commentariat have often misread this prime minister and have been left looking like chumps as a result. But where Boris has succeeded is in defying the rules of politics and the circumstances of Sajid Javid’s departure have more to do with the rules of governance. Robert Peston says: ‘The PM and [Dominic] Cummings believe the success of the government in these challenging times require Downing Street and the Treasury to act, as far as possible, as one seamless unit.’ Boris, Peston is told, ‘admires how Cameron and Osborne acted as a two-headed single political monster’.

Javid walked out of government after refusing to agree to the sacking of his special advisers and the creation of what the FT calls ‘a joint team of special advisers… to run both Number 10 and the Treasury’. However, he has not rejected the Cameron-Osborne model because that is not really what Boris — let’s do away with the pretence: what Cummings — was proposing. Cameron and Osborne worked in harmony because they were effective co-leaders of the Conservative Party and the government. Osborne could challenge his old friend’s decisions and overall direction because that was the kind of relationship they had. Javid would not have enjoyed a relationship of equals with Boris and nor will Rishi Sunak.

Sunak is five years older than I am and in the Cabinet for the first time. With the greatest respect to him, he will not be standing up to the Prime Minister (or Dominic Cummings) any time soon. He wasn’t appointed to do so. Number 10 intends to pursue a political programme for the early years of Brexit Britain that will frustrate the institutional fiscal prudence of Number 11 (and the economic dogma of the Conservative Party). It cannot afford a Chancellor who thinks fiscal policy should be set by the Treasury. The Prime Minister’s ‘one seamless unit’ is not a merger but an annexation.

This might make the politics of what comes next much easier for Number 10 but politics is not the same thing as governance and good governance thrives on give and take, ideas proposed and tested, and compromises struck where necessary. Remove that dynamic and you’re left with a prime minister no one dares to question — government by echo. The UK hasn’t had meaningful Cabinet government since the Callaghan years (the only fights Thatcher’s ministers won with her was their resignation statements) but the Chancellor was the last office with something approaching parity with the prime minister. The money is what matters and you don’t want a prime minister doing anything rash with it.

Boris has swept all that away. He’s not the first prime minister who thought of bringing the Treasury to heel but others ultimately decided against it. Life would have been so much easier for Tony Blair if he had just sacked Gordon Brown but he was held back by more than concern about internal party factions: he understood that the divide between political will and economic realities was a load-bearing wall. In Australia, where the TB-GBs played out a decade earlier between Bob Hawke and Paul Keating, the Labor government could sometimes be crippled by a political stalemate between prime minister and treasurer, but more often their clashes powered a dynamic, reforming administration that transformed Labor’s fortunes and that of the Australian economy. Where Hawke was too shy of conflict, Keating pushed him into major reforms. Where Keating was too impatient, Hawke moored his treasurer to the hard facts of public opinion. Hawke’s widow and biographer Blanche D’Alpuget called it ‘a very creative tension’ that ‘worked extremely well for the government and for the nation’. Keating once wryly remarked: ‘Prime ministers are very useful to a treasurer.’

Boris may well proceed from good intentions: we need to make Brexit work and sometimes hurdles have to be cleared roughly. But a Tory should grasp the perils of good intentions and understand that the hurdles were put in place, and kept there, for a reason. A Tory should appreciate that an imperial prime minister might ‘get things done’ but the impulse to get things done, custom and convention be damned, is not that of a conservative. Politically, the PM has stamped his authority in vivid fashion and has earned himself a wicked smile at the latest meltdown from a commentator class that never learns. But I’m not so sure he hasn’t done his government some longer-term structural mischief. Chancellors are very useful to a prime minister, and very useful to good governance.