Starring David Walliams in a TV version of his own book, it tells the story of 12-year-old Joe who has everything he could ever want from his billionaire father Len except for a friend.The cast includes John Thomson (The Fast Show, Cold Feet) as Len and Catherine Tate (Doctor Who, The Catherine Tate Show) as Sapphire Diamond, a 40-something hand model who still likes to pretend she’s 21 and is dating Len for his money.Playing Joe’s shy and very nervous head teacher is James Fleet (Vicar Of Dibley, Partners In Crime) while Rebecca Front (The Thick Of It) has been cast as Joe’s firm but fair, opera-loving teacher. Walliams (Little Britain, Big School, Britain’s Got Talent) plays Mrs Trafe, a dinner lady at Joe’s school who is described as "dirty and old and dreadful at cooking".