Sir Oswald Mosley was a British politician in the 1920s and 1930s who held fascist beliefs.
In 1936, King Edward VIII planned to dissolve Parliament and replace it with one more loyal to him, with the help of fellow Nazi sympathiser Oswald Mosley. The plan was thwarted by the Doctor, Peri Brown and Winston Churchill. (PDA: Players) In 1940, Mosley was imprisoned for supporting the belief that Britain should ally itself with Germany in World War II.
In an alternate timeline in which Germany won the war, Mosley was released from prison and became Prime Minister, replacing the executed Churchill. (NA: Timewyrm: Exodus)