Jack Guest took up rowing in 1924 and, by 1928, was good enough to compete in the Diamond Sculls at the Henley Royal Regatta, then the equivalent of a world championship in the single sculls. He was defeated in the semifinals by another Canadian, Joe Wright, Jr., but decided to join with Wright to form a double sculls crew capable of contending at that year’s Summer Olympics. At the Games they survived to the finals, where they were defeated by the American duo of Charley McIlvaine and Paul Costello, and took home a silver medal. Guest was Canadian champion in the single sculls in 1929, but lost again to Wright at the Diamond Sculls, who was in turn defeated by Bert Gunther of the Netherlands in the final. Guest then embarked upon an intense, year-long training regimen and entered the Diamond Sculls again in 1930. This time he did not meet Wright, but instead faced Gerhard Boetzelen of Germany in the finals, who had earlier bested Wright. Guest triumphed easily and retired from active competition immediately after.
Guest remained active on the rowing scene as an administrator, most notably as the president of the Don Rowing Club of Mississauga, where he had spent most of his non-Olympic competitive career, from 1938 through 1952. He also managed the Canadian rowing delegations to the 1956 Summer Olympics and the 1962 and 1966 British Empire and Commonwealth Games and was the first Canadian representative at the International Federation of Rowing Associations. Additionally, he was director of the Canadian Olympic Committee (then the Canadian Olympic Association) from 1960 through 1968. He was inducted into Canada’s Sports Hall of Fame in 1955. The Jack Guest award is given annually to the junior single sculler of the year by Rowing Canada. His son, Jack Guest, Jr., was also an elite rower who would have competed at the 1952 Summer Olympics if not for an injury that required surgery.
Canada