 At first playing mostly smaller roles and understudying larger ones, by 1942 Walker had been promoted as a principal baritone of the company, playing roles like Pooh Bah in "The Mikado".His total of thirty-five Savoy Opera roles is the D'Oyly Carte Opera Company's all-time record.After leaving the company, Walker and Roberts were engaged in Australia by J. C. Williamson to Australia and New Zealand throughout the 1950s and early 1960s in Gilbert and Sullivan as well as other works in their repertory.