3/13 Cardiff, 1869: when the dead start walking and creatures made of gas are on the loose, Charles Dickens proves to be an unlikely ally for the Doctor and Rose when they try to find who is behind it all. The episode is written by The League of Gentlemen's Mark Gatiss and guest-stars Simon Callow.
Doctor Who Confidential is 7.45pm on BBC3.
Their mutual friend: p16; Alison Graham 's verdict: p61