From Gemma Chan’s site:
Gemma has just been cast in TRUE LOVE, a new 5 part drama for BBC1 from BAFTA-winning writer/director Dominic Savage. The all star cast will also include David Tennant, Billie Piper, David Morrisey and Jane Horrocks and begins shooting in September.
Gemma Chan, btw, played Mia Bennett in the Doctor Who episode “The Waters of Mars”, Soo Lin in Sherlock, and Charlotte in Secret Diary of a Call Girl.
Waiting on another link so we can give you more info.