 Guest appearances included Phil Davis as Jefferson Hope , Paul Chequer as DI Dimmock , Zoe Telford as Sarah , Gemma Chan as Soo Lin Yao , John Sessions as Kenny Prince , Haydn Gwynne as Miss Wenceslas , Deborah Moore as one of Moriarty 's victims and Peter Davison as the voice @-@ over in the planetarium . Series two 's " A Scandal in Belgravia " featured Lara Pulver as Irene Adler , while " The Hounds of Baskerville " featured Russell Tovey as Henry Knight . In the final episode of series 2 , the role of Rufus <unk> was played by Edward <unk> , while Katherine Parkinson played journalist Kitty Riley . The first episode of series 3 featured Derren Brown . 
