Macklin Leslie Hancock was born in 1925 in the hospital that his grandfather had founded and built in Nanjing, China 33 years earlier. The Macklin and Hancock families were forced to leave China in 1927 during the Nationalist Revolution, and returned to Canada.
He was the chief planner of the team that designed Don Mills. The development company was owned by E. P. Taylor and the president was Karl Fraser, Macklin’s father in-law. When the project was announced, the city wondered about the feasibility of this ambitious development on 2000 acres centred on Don Mills Rd. and Lawrence Ave. E., which promised to provide mixed-income housing for 30,000 people and work for 25,000. Macklin’s plan focused on traffic-free neighbourhoods connected by walkways and parks.
Don Mills was the first comprehensively planned community in Toronto. Divided into quadrants, it had a clearly defined town centre which has withstood the test of time. It was comprised of an office and major retail component, middle and secondary schools, plus a surrounding mix of townhouses and low-to-medium-rise apartments. Extensive business parks, which included a mix of service commercial, offices, and industries, were located on the southern and northern peripheries. The parks and open space system, linked by trails, was revolutionary for Canadian community design. The immediate success of Don Mills made it clear that full build-out would be achieved much sooner than expected. With foresight and vision that was rare in those years, Mack encouraged management to embark on what was to become the largest private land assembly ever put together within a major market area in Canada. As early as 1954, Don Mills Developments commenced acquiring the western half of the Credit River watershed. In 1956, a few of the Don Mills planning team established Project Planning Associates, a multi-disciplinary planning, engineering and landscape architecture consulting practice with Mack as president. Under his leadership, it became the preeminent planning firm in Canada.
Macklin was also a Fellow of the Canadian Society of Landscape Architects. He was awarded a Lifetime Achievement Award by the CSLA in 2009 and served as the President of both CIP and CSLA. He was awarded the Centennial Medal for Distinguished Service to Canada in 1967, a Doctor of Science (honoris causa) from the University of Guelph in 2002, and the Order of Ontario in 2003.