Murdoch made his professional stage debut in March 1927 at the Kings Theatre, Southsea, in the chorus of "The Blue Train", a musical comedy starring Lily Elsie and directed by Jack Hulbert. He remained in the show when it opened in the West End in May of that year. He graduated from the chorus to a supporting role in a tour of "Oh! Letty", a "musical farce" in which he was praised by Neville Cardus for "a stretch of distinguished dancing". In 1932 he married Peggy, daughter of William Rawlings, solicitor. They had one son and two daughters. During the 1930s he gained increasingly prominent roles in musicals and revues, including the secondary romantic lead to Jack Buchanan's star, in "Stand up and Sing" (1932), and the lead in a 1936 tour of "Gay Divorce" in the part played in New York and London by Fred Astaire.