Our prime minister is now the embarrassing party guest who has outstayed her welcome

All that remains for Theresa May is her legacy. Such as it is. Being regarded as one of the worst ever prime ministers is something of a hollow crown, and for the past few weeks she has been visibly vanishing before our eyes. A flickering hologram at best. Now she enters rooms almost unnoticed, the embarrassing guest who has outstayed her welcome at a party that was over before it had even really begun. But still she rages against the dying of the light, determined to give one more speech to remind us all why she would so soon be completely forgotten.

For her latest final valediction – no one can rule out further acts of self-destruction with final, final speeches – May had chosen a basement room of the international affairs thinktank Chatham House. She had also asked for five seats to be removed from the room, so that no sketch writers could witness her humiliation. Unfortunately no one had warned her it was to be televised. There’s going to be hell to pay when she finds out, for what followed was – even by her own standards – a complete car crash.

Here was a speech of such staggering lack of self-awareness that the prime minister could only have been auditioning for a post-Downing Street job as her own Maybot tribute act. A secondhand toy of such limited artificial intelligence, its code wasn’t even written in binary. Just a babble of thoughts in noughts. She would have been more convincing if she had just remained silent for the entire 25 minutes.

May began by taking us through some of the greatest hits of the last 30 years, pointing out that in many ways the world was a far better place now than it had ever been. It was just a shame that she hadn’t been able to resist the temptation of trying to make it a whole lot worse. An endeavour in which she had been almost wholly successful.

She deplored the rise in populism, apparently oblivious to the fact that she had played a leading role in it. Demonising foreigners with Go Home vans in Operation Hostile Environment, pandering to the right wing of her own party and playing dumb when it suited her as judges were branded “enemies of the people” and remainer MPs were marked out as saboteurs.

What was required was compromise, she added. This from the woman whose whole career had been characterised by an inability to compromise on anything. Whose negotiating red lines and determination to put her party first had brought the country to its knees. Who couldn’t even reach a compromise when her own deal had been voted down three times, because by then the battle lines were too well set. Who was so secretive she wouldn’t even let her shadow know what she was doing.

Halfway through, many in the audience were beginning to wonder if this was all some kind of bad joke. That this was May’s belated attempt to prove she had a sense of humour.

But it wasn’t. She actually believed every word, when all she had done was written a letter to her younger self about how she should have behaved if only she could have given herself another chance. A sliding doors moment. An unwitting piece of catharsis that should have been shared only with her therapist. An apologia for her real legacy of leaving the country in the hands of someone even more unfit to be prime minister than herself. A liar and a conman.

May’s tragedy is that her unconscious self is only too aware of her failure and can’t help letting it leak out on every occasion. She’s desperate to be if not loved then at least respected, but everything she now touches turns to dust. An obsolete 1980s Amstrad computer incapable of even communicating with itself. A woman with the reverse Midas touch, who in trying to remind people of how right she was, only reinforces their knowledge of her limitations.

As she had demonstrated earlier in the day when, with more than a little help from Jeremy Corbyn – whose own incompetence grows by the day – her failings had been given their now traditional airing at prime minister’s questions. “You’re an antisemite,” she had said. “And you’re an Islamophobe,” the Labour leader had countered. And this was it. Two people passing themselves off as leaders, refusing to take any responsibility for the racism in their own party because the other was just as bad.

It was a moment of national shame. The only positive was that there was almost no one in the Commons to watch it. May’s airbrushing out of history is almost complete. If it weren’t for the imminent arrival of Boris Johnson, it can’t come quickly enough.