The competition between two prestigious eighteenth-century London concert societies, the “Professional Concerts” and the “Salomon Concerts”, is legendary. On several occasions the promoters of the Professional Concerts attempted to entice Joseph Haydn away from Salomon, but the composer remained loyal. Finally, in 1791, not to be outdone, the Professional Concerts brought over another Austrian composer, the young, highly talented Ignaz Joseph Pleyel (1757-1831), a Haydn pupil whom the master regarded with great affection. Engaging Pleyel was by no means a chance, stopgap measure or a cause for embarrassment: this was indeed a serious challenge. In a letter dated 24 April 1784 Mozart wrote to his father that he thought Pleyel was a very good composer and would one day become Haydn’s heir.