World Disarmament Conference
Noel-Baker lost his seat in 1931, but remained Henderson's assistant while Henderson was president of the World Disarmament Conference in Geneva in 1932 to 1933. He stood for Parliament again in Coventry in 1935, unsuccessfully, but won the Derby by-election in July 1936 after the sitting Derby Member of Parliament J. H. Thomas resigned. When that constituency was split in 1950, he transferred to Derby South.