In 1946, after the end of World War II, he rejoined D'Oyly Carte as principal tenor, immediately playing Tolloller and Nanki-Poo in The Mikado.
From 1946 to 1959, he regularly played the roles of the Defendant, the Duke of Dunstable in Patience, Tolloller, Colonel Fairfax in The Yeomen of the Guard, Marco in The Gondoliers, Mr.
"[3] The Gramophone called Osborn "one of the most melodious Ralph Rackstraws that the D'Oyly Carte Company have ever produced … finely characterised, beautifully enunciated and with some ringing top notes.
"[4] Osborn left the D'Oyly Carte company in November 1959,[5] to enter the retail business in Surrey, occasionally directing amateur productions.
Pinafore (1949), Frederic in The Pirates of Penzance (1950), Nanki-Poo in The Mikado (1950), Marco in The Gondoliers (1950), Richard Dauntless in Ruddigore (1951), Fairfax in The Yeomen of the Guard (1951), Tolloller in Iolanthe (1952), the Duke in Patience (part only)[n 1] (1952), and Cyril in Princess Ida (1955).