It is almost a year to the day since it finally dawned on most Conservatives that Boris Johnson would ultimately have to go. And yet, a whole two prime ministers later, it’s almost as if he never left. This time last May, he was trying to bluster his way out of trouble following the publication of Sue Gray’s report describing how cleaners found wine stains up the walls after lockdown-busting parties in Downing Street. Fast forward a year and here he is again, cornered at an airport, harrumphing that it’s “absurd” to think he might have done something wrong just because Cabinet Office lawyers working on his defence at the Covid inquiry identified from his own diaries several new potential breaches of Covid regulations requiring investigation. (If this is the defence, imagine the case for the prosecution.) Back to the drawing board for the cross-party Commons privileges committee, then, which had almost finished its report on whether he lied to parliament about lockdown parties and must now be wondering whether this will ever end. All that has changed since last May, somewhat disturbingly, is the Johnson camp’s increasing willingness to blame his troubles on a supposed political stitch-up. It’s not the first attempt to paint him as the victim of some sinister deep state conspiracy, rather than the incompetent author of his own downfall. But the idea that the people’s Brexiter was hounded out by anything other than his own exasperated party is as ridiculous as it is dangerous, given its potential to breed paranoia and hate. A Johnson comeback has never, thankfully, looked less likely. Yet nor is he going away, and therein lies the problem. Rishi Sunak pitched himself as an earnest new broom, here to sweep up all the mess, but increasingly it looks as if the mess is winning. There’s just so damn much of it: leaking from every Whitehall orifice, staining everything the new regime touches, setting MP against MP. “FFS who on earth is spouting this bonkersness? Are you determined to turn our party into a skip fire?” inquired the former minister Jackie Doyle-Price this week in one of those MPs’ WhatsApp chats inevitably destined to be leaked, after angry Johnson supporters threatened to make life even more difficult for Sunak than they usually do in retaliation. Well, nobody ever accused Johnson of selflessness; if he’s going down, he’s quite capable of taking others with him. Delicious as that prospect may be for some, however, the idea of this toxic circus descending on a Covid inquiry meant to offer thousands of bereaved people a final chance to understand what happened to their loved ones is not a comfortable one. For Sunak, this inquiry is an awkwardly public reminder in the run-up to a general election of so much he would rather the public forgot: the lonely Covid funerals, the livelihoods lost, the sacrifices made only to discover that Downing Street was seemingly laughing at us behind our backs. But it also ties him far too closely for comfort to the vengeful predecessor under whom he served. This week’s pre-trial skirmishes – with Heather Hallett, the inquiry’s chair, threatening the Cabinet Office with criminal sanctions if it doesn’t hand over Johnson’s unexpurgated notes and WhatsApp messages by Tuesday – may only be the beginning of delicate negotiations about what might and might not be disclosed, conducted between people with no reason to trust each other. Too many of the inquiry’s biggest witnesses – from Johnson himself to his former adviser Dominic Cummings and health secretary Matt Hancock – now find themselves outside the tent with nothing to lose and plenty of scores to settle, raising the risk of them forming a circular firing squad. The first public hearings, pencilled in for June and July, cover Britain’s preparedness for a pandemic and are likely to be more painful for Jeremy Hunt (who was health secretary in the run-up) than his boss. Sunak’s own role as chancellor during the pandemic, particularly in challenging lockdowns he knew would be economically crippling and in launching an “eat out to help out” scheme some fear may have helped drive a resurgence of the virus, will come under the microscope during the second phase, which will also hear from his embittered and wildly unpredictable successor. It’s surprisingly hard even for his supporters to work out what Johnson is planning, but it is hard to think of a former grandee less likely to take one selflessly for the team. If he cannot have a continued career in politics then he will want a lucrative one beyond it, which requires some restoring of his reputation: most likely he wants what he always wants in a competitive situation, to emerge the winner. Unlike Theresa May, who after she was dethroned delivered regular withering rebukes over policy to her successor, Johnson rarely attacks Sunak over anything specific. Like a bird of prey spotting some juicy roadkill, he swoops opportunistically on a row occasionally, but there’s no real sense of what he wants from Sunak beyond perhaps for him to fail, which makes him unusually hard to buy off. Having never really known exactly what he wanted to do with the power he sought, he still doesn’t appear to know now, which doesn’t necessarily stop him wanting it. And it’s this emptiness at the heart of the Johnson project, as much as the sleaze engulfing it, which is making Sunak’s life so difficult now. For all the reckless things Johnson did, perhaps the bigger problem bequeathed to his successor is all the things he never got around to doing. For better or worse, Margaret Thatcher and Tony Blair reshaped this country in profound ways and subsequent prime ministers have had to reckon with their substantial legacies. The last 13 years of Tory rule, by comparison, have left few footprints on the sand. How is Britain changed? There’s Brexit, obviously, but delivered with none of the benefits leave voters expected: no great unleashing of prosperity, immigration higher than ever, the left-behind seemingly more neglected than ever. Who feels better off now than they did in 2009? If this period has been one long economic car crash, the Cameron coalition government could at least claim some kind of social legacy; legalising gay marriage, say, or even rolling out the use of phonics in teaching children to read. But Johnson’s administration has little to show for a landslide majority but a litany of excuses. Even before Covid paralysed his government, he never developed a serious theory of what he was in power to achieve: instead he promoted mediocrities, promised what he should have known he could not deliver, and created in Downing Street a machine whose purpose was not to drive progress across Whitehall but to sustain this vacuum in power. As Cleo Watson, formerly Cummings’s chief of staff in No 10, put it this week: “I feel that it was a once in a lifetime opportunity to do things differently and it got frittered away.” Now the consequences of all that frittering are coming to light. Those 40 hospitals Johnson vowed to build, symbolising that Brexit promise to repatriate money from Brussels to the NHS? It’s long been clear they were something of a mirage – many were merely extensions and renovations – and last week it emerged that one in five will not be finished by the 2030 deadline. Levelling up? A hollow joke. Johnson’s final vengeful act on the way out of the door was to promote Liz Truss as his successor, doubtless hoping she would implode and create an opening for his triumphant return; instead she triggered a financial meltdown of which Labour will gleefully be reminding voters all the way to the ballot box. The news that she is about to embark on a national roadshow with GB News suggests she is almost as keen as Johnson to keep that skip fire burning. The truth is there just isn’t enough time left for Sunak to turn all this around in the year and a bit he has left before an election. The Conservative party finally mustered the courage to get rid of Johnson in the summer of 2022 because a critical mass of MPs feared he would cost them their seats. What seems to be dawning on some only now is that by then, they were probably already two and a half years too late. Gaby Hinsliff is an Observer and Guardian columnist