Blon Fel-Fotch Pasameer-Day Slitheen portrayed by Annette Badland and Alan Ruscoe, was a member of the nefarious Slitheen crime family. She appropriated the identity and appearance of Margaret Blaine, an MI5 official who was killed by the Slitheen so that her skin could be used as a disguise. The Ninth Doctor met her in Downing Street in "Aliens of London" when she and her family tried to push the Earth into a nuclear war, and use the remains of the planet for fuel. She was apparently killed when the Doctor helped Mickey Smith blow up No. 10 with a missile. It was later revealed in "Boom Town" that while the rest of her family had been killed, she had teleported out at the last minute. She had then gone on to become the lord mayor of Cardiff in the six months between the stories, and was planning to use the Cardiff Rift in conjunction with a planned nuclear power station to destroy the planet and use a tribophysical waveform macro-kinetic extrapolator to ride the shockwave into space, to find any surviving members of her family. The Doctor stopped this, and was going to send her back to her home planet, even though she would be executed. She tried to use the extrapolator in conjunction with the Rift and the TARDIS to execute her plan without the Power Station, however the TARDIS console broke open and she was exposed to the "heart of the TARDIS" the time vortex and with the Doctor's encouragement was regressed to an egg. The Doctor, Rose Tyler, and Jack Harkness then took her to the nurseries of Raxacoricofallapatorius so that she could start her life afresh.