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.