Boris Johnson shredded his own reputation and premiership not Sue Gray - Andrew Vine

In particular, the spectre of Boris Johnson returns to haunt him relentlessly, all bluster and self-justification with no regard for the damage he causes to an already weakened Government.

Mr Sunak might justifiably hope that his notable achievement in forging a new and amicable agreement with the EU over the Northern Ireland deal, allied to today’s announcement on tackling illegal immigration, would show the country he is making real progress.

But the poisonous legacy of his old boss over Partygate simply won’t let him.

Mr Johnson’s determination to remain the leading figure in Conservative politics, and his seemingly unshakeable conviction that it is only a matter of time before he returns to Downing Street are aimed at undermining the Prime Minister.

Even by the dismal standards of his own time in office, the current psychodrama unfolding around Mr Johnson is extraordinary.

Facing an inquiry over whether he misled the Commons over lockdown-busting parties in Downing Street, Mr Johnson’s response has been to try to throw up a smokescreen of counter-accusations.

The possible appointment of Sue Gray, the senior civil servant who investigated Partygate, as Labour leader Sir Keir Starmer’s chief of staff has been a gift to Mr Johnson.

He and his acolytes are now busy trying to undermine Ms Gray’s reputation for impartiality in order to save his own skin, by suggesting that the damning report into drink-fuelled shenanigans in Number 10 were a Labour-inspired stitch-up.

Nonsense. Mr Johnson’s reputation and premiership were shredded by one person – himself. He became – and remains – electoral poison because of his refusal to follow rules obeyed by the rest of Britain and that’s why his own MPs forced him out.

The country did not need Ms Gray’s report to know what had been going on under Mr Johnson’s roof whilst everybody else avoided meeting other people.

It was the media, not her, that exposed it all – the drunkenness, the tables full of empty bottles, the pictures of a Prime Minister with a glass in his hand. We knew all about the scandal, the hypocrisy and the cynicism before anybody outside the civil service had even heard Sue Gray’s name.

All her report did was to confirm for the official record what had been happening and offer a verdict that the public had already reached – that this was blatant law-breaking.

With all due respect to Ms Gray and her distinguished record as a public servant, for a mass of British voters disgusted by Partygate, her work was entirely superfluous.

Despite all the sound and fury of a cabal of Tory MPs accusing her of bias, there is not a shred of evidence that she was anything other than scrupulously impartial.

The Labour leader has scored an own goal by announcing her appointment to his team whilst a Parliamentary investigation into Mr Johnson is ongoing, but that is an entirely separate matter.

But from Mr Sunak’s point of view, the whole thing is monstrously unhelpful as he and the Chancellor put the finishing touches to the Budget later this month, in which the continuing cost of living crisis and getting the country’s finances on an even keel will be key factors.

All the focus is back on what so many people regard as the Conservatives’ capacity for scandal and their seemingly unshakeable obsession with a discredited leader who puts himself centre stage at every opportunity.

If Mr Sunak gives any ground to the bring-back-Boris brigade in their accusations against Ms Gray, he undermines his own position and implies that the Partygate scandal was somehow not as bad as the country knew it to be.

If he condemns them, he risks further division and unrest in his own ranks that makes an already difficult premiership even harder.

From Mr Sunak’s point of view, the best thing that could happen is for the inquiry into Mr Johnson to conclude that he misled the Commons, which would possibly be the start of a process that leads to him losing his marginal seat of Uxbridge in a by-election.