The Editors of the recently published vocal score of Temistocle point out that Johann Christian Bach 'is one of the few composers in the history of music who have been equally successful in symphonic music and in opera'. A glance at C. S. Terry's thematic catalogue of Bach's works is sufficient to convince one of the wide range of the composer's musical sympathies. Indeed, Haydn and Mozart apart, there were very few musicians active in the second half of the eighteenth century who could claim such versatility. Yet the claim that Bach was a particularly successful composer of either Italian or French opera is not supported by the facts. The brilliant success of Catone in Utica at Naples and elsewhere in the 1760s and the apparent acclaim which greeted Temistocle at Mannheim in the early 1770s must be set against the fact that, during Bach's lifetime, only one of his nine remaining operas was thought fit for revival after its original run had ended. Further-more, in spite of his renown in the concert room, the successive managements at the King's Theatre in the Haymarket commissioned no completely new opera from him between Carattaco (1767) and La Clemenza di Scipione (1778). Even taking into account the part played by intrigue in eighteenth-century operatic affairs, this is scarcely the treatment successful composers for the stage received.