In the late 1950s and early 1960s, Peter Dickinson Associates designed a number of significant projects in Toronto, Ottawa, and Montréal, including the Trans-Canada Pipeline Building, the Elm Ridge Golf and Country Club, and the North Toronto Medical Building. Although not completed until after his death, it was also during this period that he designed the Imperial Bank Building in Montréal for the bank's head, Neil McKinnon. When it opened in 1962, it was the tallest building in the British Commonwealth. In January 1960 the four associates with the firm left. Shortly thereafter Dickinson appointed Peter Webb, Boris Zerafa, Jack Korbee, Peter Tirion, René Menkès, and Rick Housden as his new associates. Following Dickinson's death, members of this group would go on to form WZMH Architects.