You can read the
BBC PRESS OFFICE synopsis for the
Series 4, Episode 10 of
DOCTOR WHO at the link supplied below.
BUT, be
warned, it is
slightly spoilery in nature.
Factually, it stars
LESLEY SHARP [see above pic] playing a character called
Sky Silvestry, and
DAVID TROUGHTON [see pic below] as
Professor Hobbes.
Also to be found in the story is
LINDSEY COULSON [see below] - probably best known for playing
Bianca's mother,
Carol Jackson, in the UK soap
EASTENDERS. By an
odd coincidence it's directed by
ALICE TROUGHTON (no relation to David though).