Welch began as a musical arranger and released a pop album, Clowns in 1971, singing his own compositions. In 1973, he wrote the song "It's Gonna Be a Good War" for the film Adolf Hitler: My Part in His Downfall, based on Spike Milligan's book. Milligan and Welch would work together on several projects, with Welch composing or conducting music for Milligan's adaptations (including Paul Gallico's Snow Goose), original fairytales, and a 1978 Goon Show single "The Raspberry Song" (conducted by "Convict Ed Welch.") He frequently appeared on Milligan's variety shows Q6, Q7, Q8, and Q9, between 1975 and 1980, performing their joint compositions.