Labour’s head of discipline quit last night after it emerged she had opposed the suspension of an apparent Holocaust denier, it has emerged.

Christine Shawcroft stood down after it was revealed she emailed colleagues to demand an activist, Alan Bull, be allowed back into the party after he posted an offensive link.

Mr Bull had been suspended after he posted a link to a Facebook article titled “international Red Cross report confirms the holocaust of six million Jews is a hoax”.

But in an email sent on Sunday Ms Shawcroft, who was only appointed in January, claimed the post had been “taken out of context”, according to the Daily Mail.

Ms Shawcroft said she was “deeply sorry” for defending the post and announced her resignation. She said: "I have decided to stand down as Chair of the Disputes Panel to ensure my wrong and misguided questions on this case do not cause doubt or anxiety about our processes. "

There are calls for Ms Shawcroft, a director of Momentum, to be kicked off Labour's National Executive Committee.