The most successful horse in Ascot history is Yeats who won four years on the trot: 2006, 2007, 2008, 2009. 

But a horse is nothing without its jockey, and they don't come much better than Lester Piggott who has racked up 11 wins over his career: Zarathustra (1957), Gladness (1958), Pandofell (1961), Twilight Alley (1963), Fighting Charlie (1965), Sagaro (1975, 1976, 1977), Le Moss (1979), Ardross (1981, 1982)