 He was twice Member of Parliament for the marginal Preston South constituency, from the 1955 general election until he lost his seat at the 1964 election and again from the 1970 election until his second defeat at the February 1974.At the end of both terms he lost to the Labour candidate, on the latter occasion to Stanley Thorne.Green was a junior government minister, serving as Parliamentary Secretary to the Ministry of Labour from 1961 to 1962, Parliamentary Secretary to the Board of Trade from 1962 to 1963, and Financial Secretary to the Treasury from 1963 to 1964.