Simpson was born in Takaka in 1942. He attended Nelson College. He gained a MA from the University of Canterbury and a PhD from the University of Toronto.

He represented the electorate of Lyttelton in Parliament from 1987 to 1990, when he was defeated by Gail McIntosh, one of a number of losses contributing to the fall of the Fourth Labour Government.

Simpson had been teaching English since the 1960s at various universities. He was at Massey University, University of Toronto and Carleton University. In his last teaching role, he was at the University of Auckland as Associate Professor in the Department of English, and head of English, roles from which he retired in 2008.

He is the director of Holloway Press, set up at the University of Auckland in 1994 and named after Ron Holloway.

Simpson lives in Auckland. He is married to Helen (b. 1943 in Christchurch). They have two children.