After a lifetime close to the workings of government, I approach drafting an article about Brexit for a Sunday publication with trepidation. Both sides have said a decision will be taken on today, but not what that may be; and anyway, can you believe that any decision will really be the last?

What I do know is that both sides will be presenting the story that best serves their negotiating positions and pleases their most important audiences. Facts are in short supply; there is a plethora of spin.

“Taking back control” will summon up the blood of British patriotism. The union jack prominently displayed before the negotiating table reinforces the demand for sovereignty, while a few asides about cheating foreigners reinforce national prejudices. The leadership necessary to listen to the other side, and understand where compromises may lead, all too soon becomes a cult of nationalism led by the most extreme of partisan groupings.

“I will have my cake and eat it” is rather a good joke on this side of the Channel. It has a quite different implication for the rest of Europe where sovereignty matters as well – theirs, not ours.

I don’t know exactly where all this posturing will end up by January; but I do know that – deal or no deal – we will in theory and in practice be outside the European Union. That is the policy on which the government was elected; they have a mandate and I would not vote against their legislation. I believe that it will be seen as a Tory measure and I will have nothing to do with it. This government will be – and should be – held responsible for quite simply the worst peacetime decision of modern times. I know of members of the cabinet who believe this as firmly as I do. I cannot understand their silence.