David Behrens: Seeds of Tories' self-destruction were planted by Margaret Thatcher

Everything that could have gone wrong since 2015 has done so, and Wednesday’s developments, which saw a humiliated and humbled Mrs May on the doorstep of Number 10, demonstrated that those who have undermined the foundations of government had learned nothing.

They are the single-issue Tories who have wanted Brexit, come hell or high water, since before the term was invented – since September 1988, in fact, when Margaret Thatcher invoked the idea in a fateful speech at Bruges.

Tom Richmond: Lessons of Margaret Thatcher’s downfall lost on Tory rebels

Her insistence that Britain would resist further integration with Europe, awoke a sleeping giant on her bank benches, whose footsteps would echo through the offices of her successors. The schism would undermine the very foundations of the party.

David Cameron was swallowed whole by it, and his defence earlier 
this week of the deal he made with the devil in submitting to the in-out referendum of 2016, was the first lesson that had gone unlearned.

The second was betrayed by the 48 letters of no confidence from Mrs May’s rebel MPs, which triggered the ballot on her leadership. This was a mutiny shaped entirely from self-interest, not the national good. Not one of them had an alternative strategy to hers; indeed, there had never been a plan for Brexit, other than unreliable and downright dishonest campaign promises painted on the side of a campaign bus.

Their protestations on Wednesday night that they were merely fighting the corner of their constituents who had voted to leave the EU were disingenuous. Without the benefit of nuance on the referendum paper, we were voting for an idea, not a policy. It was the politicians’ job to fill in the details, and they have failed manifestly to do so.

The only one of their number to have actually produced a plan was the very one they were seeking to be rid of. Mrs May’s deal is a compromise, of course, but that is a consequence of the vagueness of the mandate.

The absence of consensus elsewhere was the one constant. The rebels could not agree among themselves whether they wanted to leave the EU without a deal – a scenario which would in any case be opposed by most other MPs.

We then come to the dissention in Labour’s ranks. It was an aberration of the selection process that allowed in Jeremy Corbyn, a backbencher whose 32 years in Parliament had been defined only by anonymity and by his hostility to his own party.

He would, it was widely expected, be quickly dispatched. But then came Mrs May’s disastrous decision to call another election, and to play the austerity card in her manifesto. Corbyn’s promises of fairer wealth for all – worked out on the back of a fag packet by Diane Abbott though they may have been – seemed an attractive alternative.

The Labour leader’s ability to play to the crowd is the third lesson unlearned by Mrs May’s party. There is no one in its ranks who can match his guile, and that is what will very likely see him in Downing Street by next Christmas.

But is he the force that will unify the country? Hardly. His party is even more riven than the Tories, for its divisions run much deeper than Europe alone, and its message is rooted in rhetoric, not reality. Let’s not forget how quickly he reneged on his promise last year to wipe out student loans.

A generation of Tories has grown up in the belief that Europe was a force to be resisted, but with no concept of how. Jacob-Rees Mogg, who was 19 when Mrs Thatcher stood up in Bruges, is – despite his Regency era air – the personification of this new breed.

It was not surprising that the view found favour outside the Westminster bubble. The EU is bloated and loathsome and crying out for reform, and our history since 1945 tells us that we will always vote for change when it is offered. We don’t know what we will like in the future but we already know what we don’t like in the present.

Historians will differ on who pressed the Conservatives’ self-destruct button and when, but there was never any question that from the moment it was done, it was only a matter of time before the house of cards caved in.