Sir William was a champion racehorse. He was the winner of the 1838 Grand Liverpool steeplechase, later to be known as the Grand National. Only three runners took part, with the previous year's winner, The Duke, sent off as 1/2 favourite. He finished last of the three in the race. The winner was ridden by Irishman, Alan McDonough.
One of three horses to join William Haggas over the winter from the now retired Sir Michael Stoute the son of Night Of Thunder made an instant impression in the six furlong contest ... “He doesn’t look like a sprinter at all as he is quite a leggy horse.