Greenwood lost his seat in the 1922 general election. At the 1924 general election, he was one of a small number of Liberals, including Winston Churchill, to stand as Constitutionalist candidates. These were Liberals who advocated closer ties between Liberals and Conservatives. Greenwood's candidature in Walthamstow East was supported by the local Conservative association, but not by the local Liberals, who had their own candidate, and he won the seat. After the election, when it appeared that there was no prospect of closer formal ties between the two parties, Greenwood took the Conservative whip. He continued to represent Walthamstow East until 1929, although he never held government office again.