Guest Stars Daniel Anthony as Clyde Langer Alexander Armstrong as Mr Smith Tommy Knight as Luke Smith Anjli Mohindra as Rani Chandra Ace Bhatti as Haresh Chandra Mina Anwar as Gita Chandra John Leeson voices K-9 Paul Marc Davis as The Trickster David Tennant as The Tenth Doctor Nigel Havers as Peter Dalton Zienia Merton as Registrar