 She also began to understudy the title role in "Iolanthe" and Phoebe Meryll in "The Yeomen of the Guard".In 1977, Leonard played the role of Hebe in the Royal Command Performance of "Pinafore" at Windsor Castle to celebrate Queen Elizabeth's Silver Jubilee (Leonard's husband played the Carpenter's Mate).That year, she was promoted to principal contralto of the D'Oyly Carte Opera Company, and from 1977 until the company closed in 1982, she played the roles of Lady Sangazure in "The Sorcerer", Little Buttercup in "Pinafore", Ruth in "The Pirates of Penzance", Lady Jane in "Patience", the Fairy Queen in "Iolanthe", Lady Blanche in "Princess Ida", Katisha in "The Mikado", Dame Hannah in "Ruddigore", Dame Carruthers in "Yeomen", and the Duchess of Plaza-Toro in "The Gondoliers".