Tennant on Dead Ringers

David Tennant will be appearing in the last episode of the current series of Dead Ringers on BBC2.He will not be in it as the Doctor but will be doing 'an impression', say sources.The show - well-known for Jon Culshaw's take on Tom Baker's Doctor, plus its Doctor Who and Torchwood skits - will go out on Thursday, March 29 at 9.30pm.