Chief Whip Mark Spencer removed Lewer after he identified him as the culprit following an investigation that was conducted by the government.

After a series of embarrassing incidents in which the Conservative Party’s policies were revealed in the press before being formally announced, Spencer sent every ministerial aide the same letter – but with slightly different wording, to see which one showed up in the press.

Ironically, the letter reminded recipients of the possible consequences they could face if found to be in breach of the ministerial code by leaking cabinet information, stating: “Please keep this in the forefront of your mind; the position you hold is a privilege and not a right.”

Lewer has denied that he was behind the leak, telling Politico that “In nearly 20 years of elected office, I have never leaked to the press.” In an attempt to explain how his copy was obtained by journalists, he has suggested a member of his staff might have done so, without giving further information on who he believed was responsible.

Last month, Downing Street revealed plans to deploy this so-called “canary trap” strategy to uncover who was behind the leaks.

The dismissal of Lewer comes amid an ongoing Cabinet Office inquiry to find who is responsible for giving the media details about the plans for a second lockdown before they were formally signed off, forcing Prime Minister Boris Johnson to rush out his announcement. It is not clear from Downing Street whether they believe Lewer was responsible for that.