Tennant and Piper return to Dr Who
Filming will begin this week of a one-off special episode of Doctor Who - featuring the return of David Tennant and Billie Piper - to celebrate the show's 50th anniversary, the BBC said.
The current Doctor, played by Matt Smith, will be joined by the pair in the programme. It will be the first time Tennant has returned to his role as the tenth Doctor, which lasted from 2005 to 2010.
Piper, who played companion Rose Tyler for two series, last appeared in Tennant's final episode The End of Time.
Tinker Tailor Soldier Spy actor John Hurt will co-star in the 3D anniversary show.
The first episode of the new series has already hit television screens on BBC One.