Being on one's tod is to be alone, this derives from Cockney rhyming slang.
James Forman Sloan was known by the name Tod, born in 1874 he was a world famous horse racing jockey with great successes on both sides of the Atlantic.
Born in the USA his successes there led to his demand in England where he rode horses for the then Prince of Wales and had victories in the 1000 and 2000 guineas, the Gold Cup and the St. Leger, the only major race to elude him was the Derby.
Such was his success in the UK that George M. Cohan wrote a musical about him, Sloan being immortalized as the character Little Johnny Jones who was the "Yankee Doodle Boy" of the famous song.
In 1915 Sloan wrote an autobiography "Tod Sloan By Himself", whether the title of the book came before or after the rhyming slang is not clear, although if it was after I'd have called the book "Tod Sloan, on his tod".