This autumn Britain faces a terrible choice: between the humiliation of a deal dictated by Brussels; and the chaos of crashing out of the EU next March with no deal. But it is not too late to change course.
Today I am publishing my plan for a Better Brexit.
It is a plan that everyone should be able to support: Leavers and Remainers, young and old, people who live in big cities and people who live in rural areas and small towns.
It is a plan around which the whole country can unite.
In advance of the referendum I backed the Remain campaign - mainly because I didn’t believe that leaving the EU was worth the hassle.
But as soon as the result came in on the morning of 24 June 2016, I knew where my duty lay.
Early that morning I tweeted as follows: “The people I work for have made a momentous decision. I advised against it. But they call the shots and I will now do everything I can to make a success of it.”
In February 2017 I left hospital in a wheelchair to vote for Article 50 even though I was undergoing chemotherapy at the time.
Since then I have felt that the right course was to support the Prime Minister in her efforts to negotiate a deal and I have supported the government in all the key votes on legislation relating to Brexit.
I pay tribute to Theresa May for her sense of duty and her resilience.
I admire her determination to deliver what a majority of the British people voted for. But I am afraid that her policy has failed and I can no longer support it.
In July of last year I wrote a column for the ConservativeHome website suggesting that we should decouple from the EU gradually, parking temporarily in EFTA and the EEA before negotiating a long term relationship based on a free trade agreement.
In short that we should try to emulate Norway’s relationship with the EU before moving to a position more like Canada’s.
At the time, the government was confident that it could do a better deal than that, that it would be able to secure full access to the Single Market and the Customs Union without being a member of the relevant institutions, or signing up to their rules.
Now we know better - and the government is poised to sign up to a much worse deal than the one I outlined.
A deal which would see us agree a €39 billion divorce settlement without getting anything in the return, accept an Irish backstop arrangement that threatens to separate Northern Ireland from the rest of the UK, and see us move from full membership of the EU to a transition in which we are bound by all the rules but don’t have a vote.
It is not easy to break with my Prime Minister, and the government which I support. I am an instinctive loyalist. I have never voted against my Government before.
But during the summer it has become clear that the EU is not going to accept the terms of the Chequers Agreement, and is intent on treating it as an opening bid.
Meanwhile meetings with key supporters in my constituency have brought home to me the dismay that many voters feel at what the Prime Minister is proposing.
So now, on the biggest question facing Parliament in modern times and on a decision which will have massive implications for the UK’s prosperity and security for decades to come, I have concluded that I must put my country first.
The plan I am setting out today represents our only hope of a better Brexit. After a busy few weeks consulting with lawyers, academics and other experts, I am certain that we still have time to make it happen.
But MPs will need to move quickly and act decisively. If we wait until the New Year it will be too late.
The Better Brexit plan can be found at www.betterbrexit.org.uk