Who is the most famous person alive or dead in the United Kingdom and why?

This is a very good, though subjective and difficult to answer, question. Shakespeare would be my choice because of his effect on the English language and world literature. I'm somewhat biased toward The Bard of Avon because I was an English major in college. Close competitors would be: King Arthur (debate about whether he was a real person continues), or Queen Elizabeth I, or Queen Elizabeth II, or Sir Winston Churchill, or King Henry VIII, or Saint Patrick, or The Beatles (John Lennon, Paul McCartney, George Harrison and Ringo Starr aka Richard Starkey), or.... Fellow FAQFarmers, please wade on in.
The Queen is pretty famous!