 While working in London, he also had the opportunity to compose incidental music for a number of theatre productions including scores for the Royal Shakespeare Company.Southgate returned to New Zealand in 1974, where he was able to continue working as a composer, conductor, and arranger.During the 1980s, he was a regular broadcaster on Radio New Zealand, presenting programmes on many aspects of music and on diverse composers such as Wilhelm Stenhammar, Erich Wolfgang Korngold and Aram Khachaturian.