During the 1930s and early 1940s, Walker played a variety of parts, both in his own right and as an occasional substitute. His own roles from 1932 were the Usher in "Trial by Jury", Bobstay in "H.M.S. Pinafore", Samuel in "The Pirates of Penzance", Guron, and Antonio, which he performed in a BBC broadcast from the Savoy Theatre during the company's 1932–33 London season. From 1935 he shared the role of Bouncer in "Cox and Box" with Darrell Fancourt. In 1937 he added the role of the Notary in "The Sorcerer". In 1940 he switched from Bouncer to Cox in "Cox and Box", and from Usher to Counsel for the Plaintiff in "Trial by Jury". He also took on the small roles of Major Murgatroyd in "Patience" and Second Citizen, and the next year, Second Yeomen in "The Yeomen of the Guard". Roles in which he occasionally deputised for Fancourt or Sydney Granville were King Hildebrand in "Princess Ida", the Pirate King in "The Pirates of Penzance", Earl Mountararat and Private Willis in "Iolanthe", Colonel Calverley in "Patience", Sir Roderic Murgatroyd in "Ruddigore", the title role and Pooh-Bah in "The Mikado", Wilfred Shadbolt in "The Yeomen of the Guard", and Don Alhambra in "The Gondoliers".