As Rishi Sunak was pronounced Conservative leader by the backbench 1922 Committee this week, few noticed a tantalising anniversary. It was 100 years ago this month that Tory MPs abandoned the coalition that David Lloyd George had led since the end of the first world war. The decision proved to be a Tory triumph. The party won the resulting election and, without knowing it yet, seized control of 20th-century party politics. The dauntingly successful Tory party of the democratic era dates from that period. So does the 1922 Committee’s name. Whether Sunak will be able to take that record of Tory electoral dominance into a second century is very much an open question. History casts no light on the future. The prime minister is focused not on securing another Tory electoral triumph but on avoiding an electoral disaster. A Conservative resurgence like the one that followed the realignment of 1922 remains a long way off. The most immediate evidence of that is Sunak’s decision to reappoint Suella Braverman as home secretary, less than a week after Liz Truss forced her to resign. The issue dominated Sunak’s first prime minister’s questions today, and it is not going to disappear any time soon. It is not the only potential abuse that may come to haunt Sunak’s leadership – the Boris Johnson privileges inquiry is next month and there are questions about the return to government of Gavin Williamson, who was sacked by Theresa May for leaking classified documents. For now, though, Braverman is the issue that could rattle Sunak’s carefully balanced cabinet soonest and most dangerously. At PMQs, Sunak tried to dismiss Braverman’s resignation as an error of judgment. It was much more than that. Braverman’s offence was serious: she shared an internal Home Office draft document on immigration with rightwing backbenchers. It was a breach of ministerial responsibility, and a deliberate one. It is conceivable – public details are sketchy – that she was in the habit of doing such things. What is certain is that, as a security minister – the home secretary has responsibility for MI5, borders and police – it was a breach with big implications. Home Office officials thought it was serious enough to report it to the cabinet secretary, Simon Case. He appears to have thought it grave enough to advise Truss that Braverman should go. Sunak may struggle to shut this story down and prevent an inquiry that could force his hand over whether she can continue in the job. Even if he succeeds, the appointment will do Sunak reputational harm. Rectitude is one of his assets. He prides himself on telling the truth. He resigned as Johnson’s chancellor saying that “the public rightly expect government to be conducted properly, competently and seriously”. He arrived back in Downing Street this week promising “integrity, professionalism and accountability”. The reappointment of Braverman does not square with any of that. Why did he do such a thing? He did it because he thought he had to. Partly that’s about policy. Sunak seems still to believe that neoliberal economics can coexist with restrictive immigration measures. Not many economically informed politicians believe the circle can be squared that way. Truss certainly did not, and nor does Jeremy Hunt. But Braverman’s reappointment was less an affirmation of her views than a reminder of his weakness. Her backing for Sunak at a critical stage in the contest last weekend is what has got Braverman her job back, nothing else. It is important not to be pious about this. Given the dire situation facing the Tory party, Sunak is surely right to try to unite the party. He has to overturn Truss’s preference for a cabinet based on fidelity rather than ability. It follows that this means giving jobs to some people whom Sunak would prefer not to have round the cabinet table. It is why not just Braverman, but others such as the foreign secretary, James Cleverly, the environment secretary, Thérèse Coffey, and perhaps even the defence secretary, Ben Wallace, are still there. Hug your friends close, but your enemies even closer. Sunak is not going to be the Tory party’s magic bullet. The Braverman deal underlines that. He is not as brilliant as his admirers claim. He made bad and significant errors at the Treasury. His commitment to Brexit is bizarre for someone so economically literate and who is committed to globalisation. He is politically inexperienced – and it sometimes shows. And he faces a task that is probably beyond anyone anyway. That said, in the torrid circumstances created by the falls of Johnson and Truss, Sunak is definitely the least-worse choice available. It is hugely to the Tory party’s credit that they have chosen Britain’s first Asian prime minister. But just as Tory supporters should not overstate the difference that the coronation of Sunak has made, so also Tory opponents should not understate it, either. Consider what the Tory party managed to achieve in the past week. Most strikingly of all, it put a stake through the heart of Johnson’s attempt to make the party his own. It was widely assumed by friend and foe that he would win. The story of how that was prevented will be fascinating. This could nevertheless mark the end of the Johnson era in British politics. If so, the Tory party has done us all a favour, not just itself. The good work does not stop there. The party also managed to get rid of Truss and all her fanatical advisers very efficiently, to spare themselves a Penny Mordaunt prime ministership that would surely have ended badly, and to see the back of Jacob Rees-Mogg. The 1922 Committee deserves more gratitude than it has received for all this. It devised rules that got the party out of the hole it had dug for itself by electing Truss, but without allowing the members to vote Johnson back in. Labour has been quick to dismiss the Sunak government as a massive retread, and as the Johnson government without Johnson. It is a strange form of insult, since Johnsonism without Johnson is what Sunak would want to offer – a party cleaving to the 2019 manifesto but no longer led by the chancer on the manifesto’s cover. The Tory party’s crisis is not over. In some respects it has merely entered a new phase that may be little more than a holding pattern. Hunt’s autumn economic statement, postponed now until 17 November, will be the next decisive moment. That’s when they will have to make a choice. They can cut spending, raise taxes or, most likely, attempt some combination of the two that will please few people. Against the backdrop of interest rate rises, inflation, energy price rises, strikes and a winter crisis in the NHS, it is a bleak season ahead for Sunak and his party – whether they hold together or not. Martin Kettle is a Guardian associate editor and columnist