Hugh Percival Illsley was born in Montreal February 14, 1896. He married Lilias Shepherd in 1940. They had twin daughters. Lilias Shepherd Illsley died 1978. Hugh Percival Illsley died April 19, 1992. He began studies at McGill University School of Architecture in 1914. At the same time, he joined the Canadian Officers Training Corps at McGill. He left studies to fight in World War I as a machine gunner, then as observer and then pilot for the Royal Flight Corps. On his return to Canada in 1919, he was offered his first architectural job, with the firm Ross and MacDonald. He moved to John S. Archibald Architects in the 1930s. The firm changed names several times: in 1934, the architectural firm of Archibald, Illsley and Templeton was created. Illsley later began his own firm, H. P. Illsley, which eventually bought the Archibald firm. Among his architectural projects were the Montreal Forum, the Masonic temple on Sherbrooke St. in Montreal, Manoir Richelieu, and the Post Office building at University Ave. and Cathcart St. in Montreal. He retired in 1976. Throughout his career, Illsley maintained involvement with the military. Poor health prevented him from serving as a pilot in World War II, but he helped organize the first air cadet squadron to be formed in Canada under the Air Cadet League. Illsley was the Commanding Officer. With over 300 members, the Squadron trained in Westmount High School, using the Royal Montreal Regiment Armoury for drill and recreation purposes. Illsley designed their first uniform. He tried to get money from Air Marshall Leckie for glider training for the squadron members, but was unsuccessful because Leckie wanted only power flight.