Margaret Blaine
Margaret Blaine was a senior member of MI5 in the early 21st century, at some point prior to April 2006; Blaine was murdered by a member of the Slitheen family and her skin was used to impersonate her. Blaine was present in Downing Street with her fellow Slitheen, Joseph Green and Oliver Charles; Green had taken over the government as Acting Prime Minister giving the Slitheen more power in Britain. Blaine was present when the Slitheen murdered General Asquith, and remained with Green for the rest of the crisis; taking the skins of fellow Slitheen members who had been summoned to Downing Street; and Blaine also hunted Rose Tyler and Harriet Jones. (DW: Aliens of London/World War Three)
When a missile struck Number 10 Downing Street; Blaine was the only Slitheen who managed to survive; Blaine ended up in Cardiff where she got herself elected Cardiff Mayor and advocated a plan for a nuclear power plant in Cardiff; and killed anyone who questioned her plans such as Mr Cleaver. However, the intervention of the Ninth Doctor and his companions stopped Blaine's plans and when she tried to seize control of the Tardis by holding Rose hostage, the Doctor had her look into the Eye of the Tardis, making Blaine revert to an egg; allowing her to start life again. The skin of Margaret Blaine was presumably abandoned at this time. (DW: Boom Town)
- For details on the Slitheen impersonating her, see Blon Fel-Fotch Passameer-Day Slitheen.