15:20

Labour sources said their own whips’ efforts to convince the Brexiteers in their own party to vote for the amendment had been crucial to the crunch vote, with negotiations going on into the final hours before the vote.

Leave-supporting MPs including Dennis Skinner, Grahame Morris, Ronnie Campbell and John Mann all voting for Grieve’s amendment in order to inflict defeat on the government. One party whip described the loss as a game-changer for the hung parliament.

“It has broken the dam,” the MP said. “It will be much, much easier to do it again. Rebelling once gives you a taste for it. The discipline has been broken and it shows actually that if you do risk it and rebel for something you believe in, you can make a difference.”

The numbers were so tight many MPs coming out of the chamber after the vote said they believed the government had won. Catching his eye across the chamber, Anna Soubry shook her head at Labour chief whip Nick Brown. As news began to filter through that the government had lost, the opposition benches cheered, clapped and waved their order papers.