 Grossmith was a hit as the tradesmanlike John Wellington Wells, the title role in The Sorcerer, and became a regular member of Richard D 'Oyly Carte's company. He created all nine of the lead comic baritone roles in Gilbert and Sullivan's famous Savoy Operas in London from 1877 to 1889, including the pompous First Lord of the Admiralty, Sir Joseph Porter, in H.M.S. Pinafore (1878); Major-General Stanley in The Pirates of Penzance, who is an expert at everything except "military knowledge" (1880); the aesthetic poet, Reginald Bunthorne in Patience (1881); the love-lonely Lord Chancellor in Iolanthe (1882); the sarcastic cripple, King Gama, in Princess Ida (1884); Ko-Ko the cheap tailor, elevated to the post of Lord High Executioner, in The Mikado (1885); the accursed Robin Oakapple in Ruddigore (1887); and the pathetic jester, Jack Point, in The Yeomen of the Guard (1888). On 29 January 1887, one week after the opening night of Ruddigore, Grossmith fell dangerously ill. However, by 13 February, his physicians pronounced him convalescent, and he resumed the role of Robin by 18 February. During Grossmith's absence, his understudy Henry Lytton, who would later become the principal comedian of the company, had the opportunity to perform the role in Grossmith's place.
