Among Britten’s unrecorded works, The Ascent of F6 has long looked one of the most intriguing (the BBC hold an early broadcast). Now, under the generic title ‘Britten to America’, NMC has brought together a clutch of Britten’s unrecorded incidental music for theatre and radio from the 1930s, The Ascent of F6 the main item.

Set the 23-year-old Britten a tight deadline, tie him down with limits on his forces and the results could be extraordinary. The Ascent of F6 is as bitty as anybody else’s incidental music for the theatre, but how imaginatively far-flung the bits are – a waltz, a cabaret jazz song, a Bach chorale and the ‘Funeral Blues’ (Auden’s ‘Stop all the clocks’), scored bizarrely for piano duet, percussion and ukulele, with two solo singers and chorus. On the Frontier, another Auden/Isherwood theatre project, is less engaging but still emits sparks of the same brilliance, with its bitonal choruses and instrumental glitter giving extra edge to the poets’ sharp-as-a-knife play. Paul Bunyan does not feel far away.

NMC pairs these two scores with An American in England, a BBC wartime radio series for American consumption. It is not on the same level (‘God, what trash,’ wrote Auden when he heard the broadcast), but Mark Elder and the Hallé show off its naive pictorialism with élan. Mary Carewe throws in a couple of bonus blues numbers, both rarities. All the participants are excellent, especially actor Samuel West playing a portrait gallery of characters, and NMC’s production standards are impeccable, rolling together spoken word, choruses and instruments so that the seams never show. A disc of incidental music should not be as much fun.