Sam was the younger brother of John Arnull, the first jockey to ride five Derby winners. But Sam was off the mark first, winning the inaugural Derby Stakes in 1780 on the chestnut colt, Diomed. The race was run on Thursday, May 4th and there were nine runners. The race was worth I,015 guineas.
Diomed was sold at the end of 1798 for fifty guineas and taken to America where he was resold for one thousand guineas, but died shortly after.
Sam also booted home 5/1 second favourite Assassin (1782) and 2/1 second favourite Sir Peter Teazle in 1787. Sir Peter Teazle attained the venerable age of thirty, and was still performing stud duties when he died. His son, Sir Harry, won the 1798 Derby, giving Sam his fourth win in the race.
Sam rode extensively for the Twelfth Earl of Derby (for whom Sam won the 1794 Oaks with Hemione) and for Lord Egremont.
Sam was a quiet and unassuming character. He was a very smart dresser and an enthusiastic rider to hounds. He also kept his groom as well-dressed as himself.
Sam died on 5 February 1800 aged forty.
Sam married Juliana Dawson at Wood Ditton, Cambridge on 22nd Dec 1791. They had seven children; Samuel (1792-1841), Juliana Martha (1793 -), Harriet (1794-), Sophia (1797-), Nancy (1799-) and Thomas (1800-1841).
Sam's granddaughter, Mrs Julia Tunbridge, died aged 102 in 1943.
