Fancourt joined the D'Oyly Carte Opera Company in May 1920 to succeed Frederick Hobbs, who had announced his decision to leave the company. Fancourt went on for Hobbs as Mountararat in "Iolanthe", Arac in "Princess Ida" and the title character in "The Mikado". In June 1920, Hobbs left, and Fancourt took over the bass-baritone roles, including the above parts, Dick Deadeye in "H.M.S. Pinafore", the Pirate King in "The Pirates of Penzance", Colonel Calverley in "Patience", Sir Roderic Murgatroyd in "Ruddigore" and Sergeant Meryll in "The Yeomen of the Guard". In 1921, when "Cox and Box" and "The Sorcerer" were revived, Fancourt added the roles of Sergeant Bouncer and Sir Marmaduke Pointdextre to his repertoire. He also appeared as the Usher in "Trial by Jury" in 1926, but he thought himself "simply bloody" in the role and soon dropped it. In 1921, his wife, Eleanor Evans, joined the company as a chorister, also playing some smaller principal soprano roles. She was nicknamed "Snookie" in the company; and, according to fellow D'Oyly Carte performer Derek Oldham, "she was so beautiful, was Snookie! We all fell for her, and we gave Darrell a busy time keeping us 'off'." Later in Fancourt's career, his wife was made the company's stage director and director of productions.