In case you feel that the future path of Brexit is insufficiently complicated, allow me to introduce you to . . . the Houghton compromise.

On October 28, 1971, Roy Jenkins, deputy leader of the Labour Party, had dinner with his wife in Lockets restaurant and then walked around the corner to the House of Commons and cast a vote against his own party’s three-line whip.

Accompanying him, as he strode through the division lobby, was Douglas Houghton, chairman of the Parliamentary Labour Party. And 67 other Labour MPs followed their example. The rebels were supporting Ted Heath’s motion and providing support, in principle, for membership of the European Common Market.

Mr Heath had allowed his own MPs a free vote and 33 of