You would think that with all the guest stars, known writers and directors and of course Steven Moffat hailing the upcoming seventh series of Doctor Who as the best yet, there would be little else the BBC show could pull out of its time-travelling sleeves. However, todays news that Dame Diana Rigg and Rachael Stirling will be appearing in the upcoming episode written by The League Of Gentlemens Mark Gatiss is yet another feather to the Doctors bow for more than one reason. Not only does it add to the list of sterling British actors and actresses to have appeared on the show, but it is the first time the mother and daughter have appeared together on screen. Keeping with the family theme, the episode will feature the pair as, you guessed it, a mother and daughter who share a dark secret. What is this secret? As the old joke goes, if we told you, it wouldnt be a secret. Talking about the news, Dame Diana said, The first time Rachie and I will be working together is on an episode of Doctor Who specially written for us by Mark Gatiss. How lucky is that?" Daughter Rachael added her thoughts, saying, Mark Gatiss has written a gift of a script and an on-screen relationship between Ma and I that is truly delicious. "We have never before worked together because the offers have not been tempting, but when such a funny and original script comes through you know the time has come." Doctor Who godsorry, exec producer, Steven Moffat, commented, Dame Diana Rigg, Rachael Stirling and a Mark Gatiss script - a combination of talents you could only get in Doctor Who! Frankly, I'm terrified already!"