last time during the Conservative sweep that left the Ontario CCF with only two seats in the 1951 provincial election. City of Toronto In 1938, he was elected a school trustee and served three successive one-year terms. In 1941 and 1943 he won election to serve as an alderman on Toronto City Council for Ward 2 (Cabbagetown and Rosedale) After a ten-year interlude with his involvement in provincial politics, Dennison returned to Toronto City Council in 1953 serving again as an alderman for Ward 2. In 1958, he was elected to the Toronto Board of Control. On council he interrogated other politicians and officials on conflict of interest, expense accounts, and their relationships with companies doing business with the city. He ran to be Toronto's mayor in 1966, campaigning on providing "a strong voice for labour in city affairs" and opposing the pro-development policies of incumbent Phil Givens. He was elected despite being opposed by all three daily newspapers. He was the first member of the CCF or NDP to serve as mayor of Toronto since James Simpson in 1935, and the last until Barbara Hall. He opposed the early Eaton Centre development plan that would have seen the demolition of Toronto's Old City Hall, Dennison was a pro-labour mayor but later became more conservative in response to early criticism. Serving as mayor during the Canadian Centennial, he urged the organizers of Caribana to make it a recurring event. He generally favoured development and complained about hippies and deserters from the US military flocking to the city, saying that "a few hippies and deserters are Toronto's only problem." He decided not to run again for mayor, and due to a prostate operation, watched the 1972 municipal election from a bed at St. Michael's Hospital. Retirement and death Dennison and his wife Dorothy (née Bainbridge) had a Christmas tree farm in Caledon East, where they went to get away from the city. He was also a beekeeper, and at one point, had 900,000 bees living in his Jarvis Street home's backyard. During his retirement, the Dennisons would vacation in Florida during the winter months. While vacationing in the United States, a medical emergency arose due to his, Parkinson's disease, and it finally forced him to be evacuated back to Toronto in April 1981. He died at Toronto General Hospital from complications due to Parkinson's Disease on May 2, 1981. Their only