They say there’s nothing so “ex” as an ex-prime minister, and, in the case of Boris Johnson at the moment, the man is simply invisible. When Rishi Sunak made his historic statement on the Windsor Framework to the Commons he paid tribute to the work done on the Northern Ireland Protocol by his predecessors. Cue ironic laughter from the opposition benches, given that Sunak has had to entirely rebuild the Northern Ireland Protocol negotiated by Johnson and famously sold as an “oven ready”, “fantastic” deal in 2019.

As Keir Starmer pointed out, Johnson had “told the people of Northern Ireland that his Protocol meant no forms, no checks, no barriers of any kind on goods crossing the Irish sea after Brexit. That was absolute nonsense… I have to say that as the prime minister listed all the problems with the protocol, I did rather wonder whether he had forgotten who had negotiated it.”

Theresa May did have the good grace to show up and offer Sunak some congratulations, but of the right honourable member for Uxbridge and South Ruislip there was no sign.

One newspaper quipped that like Tiberius, he had taken himself in millionaire’s playground Capri, Italy – a long way from Belfast in February. Is he in a giant sulk, unable to grasp that the successor he believes knifed him as prime minister has brought off a major coup? Is he weighing up whether he could denounce the Windsor Framework as a sell-out to the EU? With even hardline Brexiteers like Ulster Minister Steve Baker misty-eyed with enthusiasm for it, that seems far-fetched. But everything about Boris Johnson is far-fetched.

Perhaps the delay is because he knows the full significance of his next move. If he endorses Sunak’s deal, it effectively means any lingering hope Johnson has of making a comeback is over. His only prospect of doing so depended on Sunak being seen as a failure. By endorsing the new Brexit accord, he would be acknowledging Sunak as a success. But if he condemns the deal, it would signal Johnson really is ready to mount a challenge to Sunak – the biggest gamble of his career. So far, there has been neither sight nor sound of him.

Johnson’s co-negotiator Lord (David) Frost has also gone a bit quiet lately. Usually he’s more than ready to offer advice, usually of the kind that would mean the UK breaking the very treaty he had brought back from Brussels, an empty threat that did nothing to solve the problems of Northern Ireland until Sunak decided to try talking to his counterparts in the EU. Yet now this discredited pair, Johnson and Frost, have gone to ground.

Presumably, like the DUP, they’re studying the new legal text, getting some legal advice on it, trying to find fault and reasons to reject what is actually much the best deal that could have been secured in the circumstances. As Steve Baker, former commander of the ERG “Spartans” said, the prime minister has pulled a blinder, and there are now to be the absolute minimum level of checks consistent with having no border infrastructure between Northern Ireland and Ireland.

For the hard men of the DUP such as Sammy Wilson and Ian Paisley junior, it seems to be a case of them desperately trying to find ways to say “no”, men who’ve been so used to having their demands ignored (not least by Johnson) that they can’t take yes for an answer. But that’s what Sunak and the EU have just done — given them want they want.

The new deal must come as a terrible disappointment for Johnson. His empty threat, the Northern Ireland Protocol Bill, had to be paused by Liz Truss, presumably on American advice and because it was poisoning UK-EU relations; and has now been discarded by Sunak as redundant. It would have been very handy for Johnson to have used Sunak’s failure as a reason to keep the Bill, and to quietly ramp up his informal leadership campaign; but it has not turned out like that.