Dominic Cummings arriving at Downing Street today, where he has taken charge of Boris Johnson’s strategy on Brexit and beyond

In the aftermath of the 2016 EU referendum Dominic Cummings, head of the Vote Leave campaign, sent a final email to supporters with an elliptical warning.

“If we ever want to send up a signal that Westminster is cheating the vote and we need to form a new movement, you will see ‘the bat’,” he wrote.

Two and a half years later, on the day that Theresa May signed the EU withdrawal agreement, Mr Cummings sent that signal. He posted an image of the Batman logo on Twitter below four words: “Please get in touch.’’

Then, out of the public gaze, Mr Cummings began working on a new strategy to deliver Brexit.

He started rebuilding some of the networks of Vote Leave, held focus groups