Duffy joined CBC radio's Parliament Hill bureau in 1974, and became a reporter for the flagship television newscast "" in 1977. Duffy became the lead CBC television reporter on Parliament Hill and covered the elections and most of the important federal stories of the Trudeau, Clark and Mulroney governments. Duffy is primarily known for his work as an Ottawa journalist, but he has been a foreign correspondent. He covered the fall of South Vietnam in April 1975 and was one of the last journalists to leave before the arrival of North Vietnamese troops and Viet Cong insurgents.