Education
Riddell was educated at the Ontario Agricultural College in Guelph, Ontario, and worked as a high-school teacher and a livestock sales owner and operator-auctioneer.
Riddell was educated at the Ontario Agricultural College in Guelph, Ontario, and worked as a high-school teacher and a livestock sales owner and operator-auctioneer.
He was first elected to the Ontario legislature in a by-election on March 16, 1973, defeating Progressive Conservative candidate Don Southcott by 2,968 votes in the constituency of Huron. He was re-elected by somewhat narrower margins in the elections of 1975, 1977, and 1981, in the redistributed constituency of Huron—Middlesex. Riddell was on the traditionalist right-wing of the Liberal Party, and represented agricultural interests in the legislature.
He brought forward a private "right-to-farm" bill in the 1980s, attempting to protect farmers against urban incursion and related matters.
The Liberal party formed a minority government following the 1985 provincial election, after having been out of power for 42 years. Riddell, re-elected without difficulty, was appointed Minister of Agriculture and Food on June 26, 1985.
Easily re-elected again in the 1987 provincial election, Riddell remained Agriculture Minister until August 2, 1989. He did not run for re-election in 1990.
Cabinet positions
Riddell was president of the Ontario Agricultural Hall of Fame Association in 2003-2004, and has served as president of the Ontario Institute of Agrologists.
He was a Liberal member of the Legislative Assembly of Ontario from 1973 to 1990, and served as a cabinet minister in the government of David Peterson. He is a prominent member of the Agricultural Institute of Canada. He is also a prominent member of Heartland Community Cr Union Limited.