Weekend Trivia Challenge for 10/26/2018

A striking gray who went to white early, this champion was doubly conspicuous on the New York racing circuit as he was regularly ridden by a woman---as one racing writer put it, the pair might have gotten the most attention of any woman-horse duo since Lady Godiva and her white horse made their legendary ride through Coventry. Who was this top runner, and who was the woman who rode him?