42 is not the only answer!!!

To date more than 200 non-fiction works deal exclusively with 'X'. By the 1960s, 'X' had become "the symbol of a predatory aristocracy". Six periodicals about 'X' have been introduced since the early 1990s. The legend of 'X' is still promoted in the East End of London with many guided tours. The Ten Bells, a pub in Commercial Street was renamed 'X' in the 1960s, but returned to its old name in the 1980s. There is no waxwork figure of 'X' at Madame Tussauds' Chamber of Horrors, in accordance with their policy of not modelling persons whose likeness is unknown. In 2006, 'X' was selected by the BBC History Magazine and its readers as the worst Briton in history.

Identify 'X'.