Boris Johnson has found a new role for Britain’s most endangered transport mode, the bus. He throws civil servants under it. After decapitating the Foreign Office and Cabinet Office, he has rid himself of Public Health England and those he regards as to blame for recent exam U-turns, Sally Collier of Ofqual and Jonathan Slater of the Department for Education. They have gone to save the skin of that Nureyev of U-turns, Gavin Williamson.

Mind-changing has become the leitmotif of Johnson’s government. Derision would greet him if he used Margaret Thatcher’s boast to a Tory conference: “The Johnson’s not for turning.” The Guardian has kept a tally of 11 U-turns, from lockdowns and quarantines to school exam results, key-worker visas and Huawei’s role in 5G.

There is nothing wrong in U-turns. As Keynes reputedly said: “When events change I change my mind.” In the case of coronavirus, Johnson’s apologists can plead that everything has been unexpected and events constantly in flux. Governments initially floundered across Europe. In such circumstances, a U-turn may be a disaster averted.

But almost a dozen U-turns looks like carelessness. Johnson’s constant reversion to “the science” has now left the political roadway piled with wreckage. When he is not pursued by viruses he is tormented by the Furies of the age, algorithms. Once he – or perhaps his amanuensis Dominic Cummings – adored them. Now they rank with civil servants in his demonology. His most spectacular U-turn, into total lockdown on 23 March, was ascribed to an Imperial College algorithm worthy of the KGB’s finest hackers. It told him that if he refused to U-turn, 500,000 Britons “might die”. Johnson is now said to be furious.

At this point the boundary between being informed by science and being scared witless becomes academic. The issue is whether science is “on top or on tap”. Do its often spurious certainties diminish political responsibility? In his explanation of his U-turn over school face masks, Williamson contrived both to blame the science and insist it was his decision. To the BBC on Wednesday, the education secretary cited the World Health Organization, “evidence” and “advice”. In reality his decision was led by a policy change in Scotland.

In the case of the A-levels fiasco, Johnson this week blamed another algorithm, this time a “mutant” one. Ministers were warned what would happen if they let a machine warp A-levels’ crooked timber of mankind. They ignored the warning and ordered the machine to avoid grade inflation. It obeyed.

A similarly “mutant” algorithm has apparently seized Johnson’s now obsessively centralised housing policy, threatening to build over miles of Tory countryside in the south-east. Lobbyists for the construction industry told the algorithm to follow the market, and again it obeyed.

These algorithms are no more “mutant” than civil servants. They are programmed to inform the powers that be on the fiendish job of running a modern country. They cannot be accused of conspiring to undermine the government of the day. At present they must struggle to infer the objectives of a leaderless government that constantly changes its mind. The only “mutation” just now is in the prime minister’s head.

The art of government is that of handling advice. Followers of the satirical television series, Yes, Minister, thought it showed how civil servants always got their way. It did not. It showed bureaucratic efficiency and elected politicians in perpetual tension, with the outcome a compromise, an equilibrium. But the result was ministers nowadays feeling they must surround themselves with inexperienced “special advisers”.

A loyal civil service is vital to good government, be it radical or conservative. I suspect a future coronavirus inquiry will conclude that senior officials found themselves squeezed out of a shouting match between government scientists and panicking politicians. NHS medics at first dictated policy, demanding ministers tell the public to “protect your NHS” – which ended up being at the expense of care homes and cancer patients. At risk of losing their jobs, civil servants stop telling truth to power. Policy wobbles and the steering wheels spin.

There is no alternative in democratic government to ministerial responsibility, to an iron chain linking the electorate to parliament and cabinet. A growing body of Tory backbenchers are reportedly worried at the lack of leadership implied by Johnson’s U-turns. The gossip is that a still sickly prime minister is showing little interest in decision-making and largely out of the loop. Trump-like, he craves nightly appearances on television where we see him dressed in worker’s garb, waffling to “the people” in some distant province.

An old maxim holds that leaders be judged not by their brilliance but by the quality of those around them. Their “court” is their first line of defence against the daily bombardment of advice and pressure. Under Johnson that court is composed of a tiny group of cronies, inexperienced and clearly bereft of the talents of those he has dismissed. He is Henry VIII awaiting his Hilary Mantel.

This matters because the decision about to face Britain is far more serious in the long-term than any virus. It is over how to agree frictionless dealings with our immediate trading neighbours in Europe. I am reliably told there is not a single person within the penumbra of Downing Street remotely up to the job of such negotiation.