He joined the
Young Conservatives in 1950, but remained relatively inactive in politics until
1970, when he contested
The Hartlepools, a safe Labour seat. He became MP for
Arundel in the
February 1974 general election, and retained his seat until his retirement from politics in 1997. 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. He was a strong supporter of
Japanese investment in British industry. He oversaw the
denationalisation of
Cable & Wireless and the launch of
Teletext. Marshall returned to the
back benches in 1981, when
Margaret Thatcher carried out the first major reshuffle of her government. He took an interest in the fledgling British space industry, lobbying for British participation in Ariane. He was also a member of the Defence Select Committee, a role that was controversial as he was a paid adviser to
British Aerospace. He was also involved in the parliamentary-industry discussion group,
Pitcom, becoming its chairman in 1987. He was closely involved with the
Inter-Parliamentary Union, being a vice-chairman from 1985 to 1987, chairman from 1987 to 1990, presiding over its Centenary Conference in 1989, was its world president from 1991 to 1994, and was then appointed honorary life president. He was
knighted and appointed a
deputy lieutenant of
West Sussex in 1990. He retired at the
1997 general election, when the boundaries of his seat were changed. He continued his business interests in retirement. After converting to
Roman Catholicism in later life, he became a non-executive director of
The Catholic Herald in 2003. ==Outside politics==