Mr. Hennessey drove his first winner in 1943 at Summerside Raceway, directing his father Wal’s horse Dale H to a 4-2-1 summary finish, with the 2:11 victory being the fastest on the race card that day. He went on to drive 923 winners over his career.

Included among Mr. Hennessey’s more well-known horses were Royal At Law, Cheeky Chief, Dominion Byrd, My Darling, John Willie Bob and Callie Hal. Along the way he also helped many young horsemen get their starts in the business, including Ralph (Bo) Shepherd, Jack Pound, Joe Arsenault, Bert McWade, Lorne Hennessey, Maurice Hennessey and Lloyd Duffy.

Mr. Hennnessey was also instrumental in the careers of his sons, which included Danny, Jody and Gordie, besides Wally.