Verdi upon arriving late to London for the premiere of I masnadieri:
(Note: Budden, Julian. The Operas of Verdi. I. From Oberto to Rigoletto. London: Cassell, 1973.)
He had heard that Jenny Lind, the Swedish songbird, was not going to learn any more roles, and he had written the role with her in mind. Benjamin Lumley, the Impresario, had problems with singers and conductor Michele Costa earlier that year at Her Majesty's Theatre. The conductor and singers let to form Covent Garden.
Previously at Her Majesty's Theatre, when the London audience realized that the baritone singing was not their beloved Tamburini, but newcomer Filippo Coletti, the rushed the stage in protest. Coletti was cast in this new Verdi opera.
From wikipedia: "Queen Victoria and Prince Albert of Saxe-Coburg and Gotha attended the first performance, together with the Duke of Wellington and every member of the British aristocracy and fashionable society that was able to gain admission."
Not the baritone, but someone: