Imperial Lee was a 21st century man who tried to change history on a massive scale. His original name was Stanley Wainwright.
He and Lady Silk gave Ray Morita the crucial missing element for his dimensional travel formula, which was desire. Morita was a fan of Duke Ellington, so he used his formula to travel to a parallel universe where Ellington was able to record his music during the entire 1940s. He took Imperial Lee and Lady Silk with him to that time period on an alternate Earth.
Unknown to Morita, Imperial Lee planned to use the formula to trigger a reaction to destroy that universe. This would cause a ripple effect throughout the multiverse, changing history on other Earths so the Allies would lose World War II. Lady Silk could then return to her home dimension, to a Japanese-controlled Earth. Their plan was foiled by the Seventh Doctor. Unable to face his failure, he leapt to his death from a second-storey window. (PROSE: Atom Bomb Blues)