Sandford joined the D'Oyly Carte Opera Company in 1957, for the pay of £37 and 10 shillings a week (about £700 at 2007 values) He immediately assumed eight principal baritone roles: the Sergeant of Police in "The Pirates of Penzance", Archibald Grosvenor in "Patience", Private Willis in "Iolanthe", King Hildebrand in "Princess Ida", Pooh-Bah in "The Mikado", Sir Despard Murgatroyd in "Ruddigore", Wilfred Shadbolt in "The Yeomen of the Guard", and Don Alhambra del Bolero in "The Gondoliers". He dropped the role of Sergeant of Police in 1962 (which he found uncomfortably low for his "creamy and slightly breathy" lyric baritone voice) and added Dr. Daly to his repertoire when "The Sorcerer" was revived in 1971. In 1962, he played Shadbolt in a grand production of "Yeomen" staged by Anthony Besch at the Tower of London as part of the first City of London Festival. "The Times" said, "Mr Kenneth Sandford's lean, melancholy, decidedly sympathetic Shadbolt steals the show." By this time, the copyrights on Gilbert and Sullivan had expired and, to Sandford's delight, Besch's production was completely restaged, allowing Sandford to develop a new interpretation of the role.