After a career in the steel industry, he was Conservative Member of Parliament for Arundel for 23 years, from the February 1974 general election until the constituency was abolished in 1997.
He was heavily engaged with the Inter-Parliamentary Union, and had interests in theatre, cricket, golf, and wrote a number of books.
He joined the Young Conservatives in 1950, but remained relatively inactive in politics until 1970, when he contested The Hartlepools, a safe Labour seat.
In Parliament, his knowledge of the steel industry made him an effective critic of Sir Don Ryder's plan to nationalise British Leyland.
He was a member of the Select Committee on Nationalised Industries, and realised that British Steel Corporation needed major reconstruction.
He was able to implement his ideas when he became Parliamentary Under-Secretary of State at the Department of Industry in 1979, under Sir Keith Joseph, where his portfolio that included aerospace, information technology, telecommunications, the Post Office, shipbuilding, space and steel.
Marshall returned to the back benches in 1981, when Margaret Thatcher carried out the first major reshuffle of her government.
He was also a member of the Defence Select Committee, a role that was controversial as he was a paid adviser to British Aerospace.