In 1930, Leigh declined a teaching job and set about earning a living by accepting small commissions and becoming increasingly involved with the theatre.
He composed an elaborate score for Basil Wright's documentary film The Song of Ceylon and the concert overture Agincourt, commissioned by the BBC in celebration of King George V's Silver Jubilee.
The music for A Midsummer Night's Dream was written for an open-air schools performance at Weimar in 1936; it is scored for flute, clarinet, trumpet, strings and harpsichord.
The only other major commission Leigh undertook before the outbreak of war was to produce the music for Herbert Farjeon's intimate revue Nine Sharp (1938).
He was killed in action near Tobruk, Libya in 1942, just before his 37th birthday, leaving a widow, Marion, and three children, Julian, Veronica and Andrew, who had been sent to Canada to escape the London Blitz.