Boris Johnson has spent his career disguising cunning plans as unintended blunders and dressing up stupid errors as machiavellian strokes. So there has been much understandable confusion about whether the defenestration of Sajid Javid was by accident or by design. In the immediate aftermath of his resignation, Number 10 didn’t much object to suggestions that the prime minister engineered the chancellor’s removal by ambushing him with a demand to sack all his special advisers, a demand that the prime minister knew the other man could never accept. This version of events appalled a lot of Tory MPs and generated much finger-pointing at Dominic Cummings, who I won’t call the prime minister’s Rasputin because he likes the label too much.

It then suited some of Mr Johnson’s friends to spin that it was not a cunning plan at all, but an innocent cockup. Not: ha, we screwed Javid. But: oops, we lost Saj. On this account, the chancellor reacted with more hostility than anticipated when, towards the end of their conversation on the morning of reshuffle day, Mr Johnson asked him to dispense with his closest aides. The prime minister, so this story goes, was genuinely surprised and sad to lose his services.

I am usually inclined to the cockup theory of high politics, but in this case not. I have rarely heard, to use a Johnsonianism, such an inverted pyramid of piffle. Had the prime minister sincerely wanted to keep his next-door neighbour, he could have done so easily. He might have softened the demand or agreed to present things in such a way that it wouldn’t look like a humiliation for the chancellor. He did none of those things and so Mr Javid felt he had no choice but to quit. He was already being mocked as “chino” – chancellor in name only. The ridicule would have reached eardrum-busting levels if he had conceded to having his advisers replaced with servants of Mr Cummings. This was not an accident – it was a coup. They deliberately presented Mr Javid with a lose-lose dilemma: accept becoming an enfeebled figure or quit.

Shortly after he moved to No 10, Gordon Brown expressed frustration at how few resources he had compared with No 11

This is of a piece with things we already know about the Johnson-Cummings (or Cummings-Johnson) regime at Number 10. It has an intention to “march through the institutions” by intimidating or directly attacking rival estates of the realm, whether they be the CBI, the BBC or the supreme court. In his pre-Downing Street days, Mr Cummings once voiced an ambition to “break the power of the Treasury”.

The design to try to draw a lot more power to the centre by radically strengthening the writ of Number 10 is nothing like as revolutionary as they think it is. Nearly every prime minister and prime ministerial aide I have known has felt underpowered and especially envious of and aggravated by the clout wielded by the Treasury. Shortly after he moved over from Number 11 to Number 10, I recall Gordon Brown expressing frustration at how few resources he had at his disposal as prime minister compared with his previous office. The chancellor commands more than 1,100 staff at the Treasury’s Horse Guards headquarters. Less than a fifth of that number work in the rabbit warren of offices in Downing Street that serve the prime minister. The Treasury has substantial units of civil servants to monitor the performance and spending of each Whitehall department. The prime minister usually has just one adviser in each subject area. Prime ministers habitually, and not always wrongly, become angered with the Treasury’s often conservative institutional mindset and its control of the chequebook, especially when it wields that power to veto pet desires of the PM. Harold Wilson set up a rival Department of Economic Affairs. That gambit failed, not least because the drunken George Brown was in charge of the DEA. Theresa May almost instantly fell out with Philip Hammond. After two terms of arm-wrestling with Gordon Brown, Tony Blair asked John Birt, the one-time director general of the BBC, to draw up a secret blueprint to drain power from the imperial Treasury. This was aborted, like all of Mr Blair’s plans to curb his mighty chancellor.

Some of the prime minister’s friends justify the eviction of Mr Javid on the grounds that it would be bad to repeat “the TeeBee-GeeBees”. This was the Whitehall code, which I was the first to put into the public domain, for the bitter conflicts that erupted between Numbers 10 and 11 during the New Labour years. It is true that a lot of that government’s energy was squandered on their incessant battles, but the full picture is more complicated. There was also a positive aspect to the competition. Each side knew that the other would ferociously interrogate its ideas. This could have a useful purpose in eliminating rotten ones. It also incentivised both camps to be on the top of their game. The give and take of argument sometimes improved policy.

The word from the prime minister’s allies is that he desires a relationship with his chancellor akin to that between David Cameron and George Osborne, a relationship so close that the connecting door between Numbers 10 and 11 was always kept open. A major advantage of the “Dave and George” double act was that they and their teams stuck together during rough patches and almost never briefed against each other. A significant disadvantage was that it was far too incestuous. They didn’t challenge each other enough. Had there been a healthier contesting of ideas, they might have avoided some of their worst mistakes, such as the calamitous “omnishambles” budget.

This reshuffle has underlined the current primacy of the Johnson premiership. There is a rookie chancellor, no other big beast counterweights to the prime minister in the cabinet and no focus of backbench rebellion. For now. A dominant prime minister with a chunky majority is free to experiment with establishing a command and control regime designed to make an absolute monarchy of Number 10. But those familiar with previous attempts can already see why it is likely to come unstuck.

Yes, the brutal treatment of Mr Javid, given such a short time as chancellor that he did not get to deliver a single budget, will have a terrorising effect on the weak-kneed members of the cabinet. It will also serve as a warning to be heeded by shrewder ministers that they need to develop their own power bases as a defence against being treated in the same crushing fashion in the future.

By most accounts, Rishi Sunak, the new chancellor, is a smart guy. He has been appointed because he is a “golden boy” of the prime minister; that doesn’t mean he will necessarily turn out to be a patsy. Friends report that he knows that he will not win the confidence of his officials, the respect of his colleagues or credibility with business and other external actors if he is seen as a glove puppet of Number 10. He’d be wise to demonstrate an early assertion of his independence and has the scope to do so because even this prime minister is surely not so reckless as to lose two chancellors in rapid succession.

Mr Johnson, a man known more for his short attention span than for his devotion to detail, will encounter the sheer physical impossibility of trying to run everything from Downing Street. Even if Dominic Cummings is as clever as he thinks he is, he will find that an organism as complex as the government of an advanced nation can’t all be directly managed from one terraced house in SW1. To deliver on their promises, and to handle adversity when things turn turbulent for this government, they are going to need robust ministers, not a cowering clique of yes-persons. Both Margaret Thatcher and Tony Blair, exceptionally powerful prime ministers in their day, saw the value in having other strong characters around them.

Gordon Brown and Theresa May both tried the micro-managing, control-freak model of premiership and in neither case did things turn out well. Nick Timothy, who was Mrs May’s version of Mr Cummings, will next month publish a book in which that fallen consiglieri reflects regretfully on their attempt to rule by decree from Number 10. He confesses that he and Fiona Hill, his co-chief of staff, found themselves “overwhelmed”. As did their boss. “The role of the prime minister is not to play every instrument in the orchestra, but to write the score and conduct the musicians. Too often, Theresa was trying to play the strings, woodwind, brass and percussion all at the same time.”

Which brings us to another downside of trying to run government as a one-woman or one-man or one-Rasputin band. With a monopoly of power comes a monopoly of responsibility. When the audience decides it doesn’t like the music, there is only one person to boo.

• Andrew Rawnsley is Chief Political Commentator of the Observer