Peter Pratt joined the D'Oyly Carte Opera Company as a baritone chorister in September 1945 and occasionally assumed small parts. He got his big break when he was called upon to play Robin Oakapple in Ruddigore on short notice in May 1949. After this performance he was given primary understudy responsibilities to Martyn Green. With Green’s departure from the Company in 1951, Pratt took over his leading rôles and served as D'Oyly Carte's principal comedian for the next eight seasons. With the D’Oyly Carte Opera he recorded Major Murgatroyd (Patience, 1951), John Wellington Wells (Sorcerer, 1953), King Gama (Princess Ida, 1955), Ko-Ko (Mikado, 1957), and General Stanley (Pirates, 1957).After leaving the D'Oyly Carte, Pratt continued to work in theatre, television, concert, and radio programmes.