Doctor Who's newest star, Michelle Ryan, has shot her debut scenes in the sci-fi show with Timelord David Tennant.

By Daily Telegraph Reporter - 27 January 2009 • 5:55pm

Ryan and Tennant were photographed filming aboard a bus in Cardiff city centre CREDIT: Photo: WALES NEWS SERVICE

​The former EastEnders actress plays the mysterious Lady Christina de Souza in the BBC One Easter special, Planet of the Dead.

She and Tennant were photographed filming aboard a bus in Cardiff city centre, with Ryan dressed head to toe in black leather.

Ryan, 24, previously played Zoe Slater in EastEnders and had a short-lived stint in Hollywood as the star of a flop Bionic Woman remake.

Executive producer Russell T Davies has teased viewers with the disclosure that Lady Christina is a woman with a mysterious past who's going to have a huge impact on the Doctor".

Rumours are rife that she will become the full-time Doctor's assistant when 11th Timelord Matt Smith takes over in 2010.

However, a number of actresses will play opposite Tennant in the remaining 2009 special episodes, and other women linked to the role include Kelly Brook and Lily Allen.

Ryan said: "I'm a huge fan of Doctor Who and very excited to be joining David Tennant and the Doctor Who team. It's such a fantastic show and I can't wait to get started."

Comedian Lee Evans will also appaer in the Easter special as Malcolm, a character whose life "becomes connected to the Doctor's under extraordinary circumstances".