In a devastating point-by-point demolition of Chamberlain’s handling of the war, Amery told him: “We are fighting today for our life, for our liberty, for our all – we cannot go on being led as we are.”

He ended his lengthy speech by quoting the words of Oliver Cromwell to the Long Parliament in 1653 when he told them: “You have sat too long here for any good you have been doing. Depart, I say, and let us have done with you. In the name of God, go.”

Mr Davis omitted the middle sentence when he repeated the phrase from the backbenches, and Mr Johnson – visibly shocked by the challenge – claimed he did not know of the quotation to which the former leadership candidate was referring.

But for someone who wrote a book about Churchill, the speech that helped bring him to power must surely have rung a bell.