David Walliams is to play a "dirty old" dinnerlady in the TV adaptation of his book, Billionaire Boy.

The Little Britain funnyman will portray Mrs Trafe, who is also described as a "dreadful cook", in the BBC One Christmas special, which also stars Cold Feet actor John Thomson, Rebecca Front and Warwick Davis.

There will also be a cameo by a "very special" mystery guest.

Walliams, who has also co-written the script with Kevin Cecil, says: "I am thrilled we have put together another all-star cast of comedy greats for this adaptation. The script is bigger and better than the book and I am excited for everyone to see it on BBC One at Christmas."

The book tells the story of Len (Thomson), who becomes a billionaire after inventing a new toilet roll, and his 12-year-old son Joe (Elliot Sprakes), who longs to have a friend.

Billionaire Boy, the fourth Walliams' novel to be adapted by the BBC, is being made as an hour-long special that will air as part of the corporation's festive season of shows.

It follows the successes of Gangsta Granny, Mr Stink and The Boy In The Dress.

Filming on the show, which will begin in coming days in Sheffield and Rotherham, will feature local school children from Oakwood High School, Rotherham, who have been cast to appear as Joe's classmates.