The excellent and well respected Sarah Lancashire is to appear in the first episode of the fourth season of Doctor Who as the woman, Miss Foster, who is the catalyst for reuniting the doctor with Catherine Tate's Donna Noble.
Sarah Lancashire said of the role: "I'm absolutely thrilled to be in Doctor Who. It's a brilliant episode and I'm looking forward to taking the Time Lord on."
The start of the new series will see Donna tracking down The Doctor during an alien emergency in modern-day London. Donna and The Doctor will also be travelling through time for an encounter with the legendary murder mystery novelist, Agatha Christie, and taking a trip to Pompeii.
Confirmed guest stars for the fourth season include Felicity Kendal, Fenella Woolgar, Tim McInnerny, Peter Capaldi, Phil Davis and Tracey Childs.
Freema Agyeman who has played Martha Jones, The Doctor's companion throughout the critically-acclaimed third series, will return to the show to join The Doctor and Donna mid-series.
The fourth series of Doctor Who is now in production and will hit BBC One in Spring 2008.