In the spring of 1947, Lesley Duff was cast in Britten's next opera, Albert Herring, as the adolescent schoolgirl Emmie. It isn't a demanding singing role, so for Duff's self-confidence it didn't present the same problems as Lucretia. The cast met for the first playthrough at Pears's flat in Oxford Square:

John Christie, Glyndebourne's owner, had underwritten the previous year's tour of Lucretia and lost a lot of money, which had soured forever an already difficult relationship with Britten. Christie's appetite was for Mozart and Strauss. He would say of Herring to an audience member, ‘This isn't our kind of thing, you know.’ No longer under the aegis of the Glyndebourne Opera Company, Britten had his own English Opera Group. They would still perform one short season at Glyndebourne, giving both Lucretia and Herring, but as an independent company.

Britten's playthroughs were an experience shared by Duff and, later, by Steuart. The Herring playthrough was one of the few experiences of her working life she related to her son, giving him a rare anecdote from 1947:

Duff was becoming closer to Britten's inner circle. Britten and Pears were the frequent recipients of acrimonious letters from people who disapproved of their lifestyle as much as they hated Britten's music, and Duff was at Oxford Square one day when a letter arrived.

Ben came into the room holding it as if he had a poisonous snake by the tail, with a face like a sheet.