He sat as a New Democratic Party member of the Legislative Assembly of Ontario from 1982 to 1995, and was a cabinet minister in the government of Bob Rae.
He was a professor at the University of Regina from 1964 to 1974 where he initiated interdisciplinary prairie studies and founded the Canadian Plans Research Centre.
He said it ultimately failed because the concept translated poorly between English and Canadian society and that the structure of the churches did not lend itself to promoting social change.
[11] The NDP were defeated in the provincial election of 1995, and Allen lost the Hamilton West riding to Progressive Conservative Lillian Ross by over 4,000 votes.
[12] Allen moved on to become chairperson of the Board of Wesley Urban Ministries in Hamilton (1996–2001) and resumed a career of historical research and writing.