David Blunkett will answer questions on Harry Potter

He will appear in one of three celebrity editions of the John Humphrys-hosted quiz, to be screened on BBC Two later this year.

Mr Blunkett said facing Humphrys on Radio 4's Today show "will, I'm sure, seem like a picnic in comparison".

Comedy actor and director Stepehn Fry and EastEnders' Shaun Williamson will also feature among the guests.

Fry will answer questions on Sherlock Holmes, while Williamson - who plays Barry Evans in the soap - will specialise in questions on actor Richard Burton.

Other guests scheduled to appear include Poet Laureate Andrew Motion, TV bird watcher Bill Oddie, journalist Jeremy Bowen, newsreader Julia Somerville and writer and broadcaster Germaine Greer.

As usual, contestants in the famous black chair will face a round of general knowledge questions in addition to their chosen subjects.

A celebrity edition of Mastermind was first broadcast last year.