In a letter to the prime minister, he said his loyalty was “not to a man, but to this country”.
He begged him to quit his job and warned that the crisis sweeping the government would only get worse.
“This is not sustainable and it will only get worse, for you, for the Conservative Party and especially for the whole country,” he said.
“You must do the right thing and go now.”
His request to the prime minister to step down comes less than 36 hours after he was appointed chancellor.
Despite his clear vote of no confidence in Mr Johnson, the Stratford-on-Avon MP did not relinquish his position.
It is clear that he will remain in office so as not to cause panic in the financial market.
More to follow…