William Hazlitt’s advice to travellers was “take your common sense with you, and leave your prejudices behind”. It’s not bad guidance for Theresa May as she sends her Article 50 missive to Brussels.

We know there are many among the Prime Minister’s closest advisors – Liam Fox, for example – whose prejudices have always been for rupture, rather than a deal, with the EU. The question today is: does Theresa May secretly agree?

Why else choose to put Brexit Britain as far away from our neighbours as possible? Why else the foolish early threat to walk out if we didn’t perfectly get our way (thank goodness, the government is now backtracking on this)? Why else all the insult-laden invective against the 48 per cent of Remainers, which left our country more divided today than we were on the morning that the Leavers won?

'We already miss you': Donald Tusk after receiving Article 50 letter

Make no mistake: this reckless brutal Brexit, yanking us out of the world’s largest single market even before she has started to negotiate, is Theresa May’s choice.

In her letter to Brussels today, the Prime Minster said she has enacted the “democratic decision of the people of the United Kingdom”. She has done no such thing. It is not those who sought to soften the Brexit blow by challenging the Government who do not respect the Brexit vote. It is May, who has hijacked that vote to feed the anti-European prejudices of her own party.

Few in Britain voted to leave the single market; remaining in it was proposed by many Brexiteers and promised in the Conservative election manifesto. Estimates put the cost to Britain of this kind of “hard Brexit” as high as £200bn over 15 years. Already companies are leaving, taking with them livelihoods, expertise and the futures of many citizens. We are now embarked on a course that will bewilder future historians as the most remarkable example in modern history of a country committing an act of monumental self-harm while still in full possession of its faculties.

So why has May moved her party onto policies indistinguishable from those of Ukip? For the same reason that Mr Cameron insisted on the Referendum in the first place: the best interests of the nation are once again being held hostage to the internal management of the Conservative Party.

Spare a thought for those Conservatives who still adhere to their Party’s proud internationalist tradition. Who is as lonely as them now?

It is still possible to stop this madness and keep Britain inside the single market. It is even still possible for the British people to remain in the European Union. Democracy didn’t end on 23 June 2016, and it hasn’t ended today either. The people can have their say over the final Brexit deal – and they should.

Nigel Farage: I'll emigrate if Brexit doesn't go to plan

Meanwhile, the phony war of recent months, fuelled by insults against all those who dared to challenge the Government and prosecuted by a stream of completely unsubstantiated claims and undeliverable promises, is over. Now the Government will be held to account for what it does, not what it says; now we will see whether all those promises plastered on the side of campaign coaches and blithely scattered about in ministerial statements can ever be delivered.

First up will be the Great Repeal Act, devil-infested with detail and to be measured against that significant David Davis promise that no EU right, protection or advantage enjoyed by British citizens now will be diminished.

At the same time, we plunge into the most complex negotiations in our history. There is no chance these can be completed with a good deal inside 18 months. If that proves to be so, then the Prime Minister demands we all join hands with her and jump off a cliff into national isolation, accompanied by disaster for our trade, our influence and our economy.

If you feel depressed today, don’t be. Be fighting mad. There’s still everything still to fight for.