Oliver Charles' mistress

Oliver Charles' mistress was "enjoyed", along with his wife and a young farmer, by a member of the Slitheen family who had secretly killed him and used his skin as a disguise. (TV: Aliens of London)

Behind the scenes
The implication in Aliens of London of this Slitheen enjoying Oliver Charles' mistress was confirmed by Doctor Who: The Encyclopedia, which noted the disguised Slitheen had a number of sexual liaisons with her as well as Charles' wife and a young farmer.