This double CD is a treat for operetta fans. The Silent Serenade was designed to pave the way for Erich Korngold’s return to Germany after the war. Having given up writing for films in Hollywood and getting back to what he considered his main business, he began work on the piece in 1944.

The story revolves around mysterious lovers, bomb conspiracies and mistaken identities; the usual plot devices so beloved of the genre. However, Korngold fell into that old trap which bedevils much of central European operetta – that of a poor libretto. A shame, because the music is witty, bright and melodious.

It also failed, both in the US and Germany, because it had missed its time, as the excellent notes tell us. Had the work been staged in the 1930s it might have been a hit.

On Broadway, the famous producer, Jacob J Shubert, wanted to make too many changes for the composer’s taste and by the time it was sorted, Rodgers and Hammerstein had revolutionised the form of musicals. Meanwhile, “Viennese” operettas had become passé. My advice: simply ignore the book and listen to the delightful score.

The small orchestral ensemble, based around two pianos, is most effective – a...