Margaret Blaine

Margaret Blaine was a member of MI5. In 2006, however, Blon Fel-Fotch Passameer-Day Slitheen killed her in order to use her as a skinsuit as a diguise. (DW: Aliens of London / World War Three, Boom Town). At the end of the latter, the empty skin is left on the TARDIS floor; it is not known what happened to it afterwards.

Still posing as Margaret Blaine, Blon Fel-Fotch Passameer-Day Slitheen got elected Lord Mayor of Cardiff.