Born in Portsmouth, England, McDermott immigrated to Canada in 1948 and settled in Toronto where he worked as an assembler and welder at the Massey-Harris plant.
McDermott was a social activist and civil liberties advocate and joined the Joint Labour Committee to Combat Racial Intolerance soon after arriving in Canada working with the committee to lobby for the enactment of Ontario's first Human Rights Code.
[3] As UAW Canadian Director, McDermott led a campaign against wage controls being implemented by the government of Pierre Trudeau in 1975.
Under McDermott, the CLC organized a 100,000 person protest against the federal Liberal government's economic policies in 1981.
[3] Following his term as CLC president, McDermott was appointed Canada's ambassador to Ireland in 1986 and served in that position until 1989.