Dame Diana Rigg and her daughter Rachael Stirling will appear in the upcoming Season/Series of DOCTOR WHO.
Character details remain under wraps, but the episode penned by Mark Gatiss will see Dame Diana and Rachael recreate their off-screen relationship on-screen, as they play a mother and daughter with a dark secret.
...says THIS piece over at BBC. BBC indicates the duo's episode will be scripted by Mark Gatiss, who previously wrote DW Season/Series 5 and/or 6 episodes like Victory of the Daleks and Night Terrors, and is an Executive Producer/Writer alongside DW overboss Steven Moffat on the amazingly excellent SHERLOCK (on which he also appears as Sherlock's brother Mycroft).
Rigg is, perhaps, most famous for portraying the ass-kicking Emma Peel in the legendary AVENGERS television series...
...and for playing Teresa di Vicenzo, ill-fated wife to George Lazenby's James Bond, in ON HER MAJESTY'S SECRET SERVICE.
Stirling's extensive acting career has recently escalated to include high-profile fare like SALMON FISHING IN THE YEMEN and the slightly-dull-but-generally-quite-good SNOW WHITE AND THE HUNTSMAN.
No word on when DOCTOR WHO Season/Series 7 will debut, but indications...both official and otherwise...suggest it'll be rather soon. Asylum of the Daleks, the first episode of said new Season/Series, will premiere at BFI on August 14.