After beginning his career as a Liberal councillor in Wallasey in the 1960s, he joined the Labour Party and was elected Member of Parliament for Goole at a 1971 by-election.
[2] As the Chair of the Select Committee on Trade and Industry, and as Chair of the Select Committee on the Channel Tunnel Bill, Marshall played a notable role in the development of Channel Tunnel project.
He stood to be the Labour candidate in the seat of Doncaster North, but lost the selection to Michael Welsh.
Marshall was the author of two published books: Parliament and the Public (Macmillan, 1982) and Business and Society (Routledge, 1993).
[2] In 2019 he married Margaret Anthea Masding (née Martin Smith) in Oxford.