Sherilyn Harper was the leader of the far right New Britannia Party.
In 2002, her party ran in the United Kingdom general election. Her campaign was based on stirring up fear of those who opposed the British way of life, particularly ethnic minorities. Together with her aide and campaign manager Roderick Allingham, she secretly funded the United Front to frighten people into supporting them. Stephen Keyser and Walter Jacobs believed she was the host of the Fearmonger and tried to assassinate her, but both attempts failed. Later, when she was interviewed on Mick Thompson's radio show, the Seventh Doctor attempted to destroy the entity within her, only to find that she was not, and never had been, its host. The Fearmonger continued to feed on the fear generated by Harper's rhetoric and the Front's activities, which eventually led to riots breaking out in London. The Doctor stopped the riots by exposing the link between the NBP and the Front, then spoke with Harper at party HQ, leaving her to the mercy of an angry mob which was coming for her. (AUDIO: The Fearmonger)