Planché held the position of stock author (in-house writer) at the Adelphi for a short period in 1821, before moving to a similar position at the Theatre Royal, Covent Garden. In 1822 he wrote the libretto (and some of the music) for his first full-scale opera, "Maid Marian; or, the Huntress of Arlingford". In 1826 he wrote the libretto for another opera, "Oberon, or the Elf-King's Oath", the final work of composer Carl Maria von Weber, who died a few months after its completion. While this opera was a commercial success and received a favourable critical response at the time, subsequent critics have not appreciated Planché's libretto.