Original: Upon their return to England in 1942, they performed Britten's Seven Sonnets of Michelangelo together at Wigmore Hall on 23 SeptemberOliver, Michael (1996) Benjamin Britten, Phaidon, p. 96, and then recorded them for EMI, their first recording together.
Simplified: Back in England they performed Britten's song cycle Seven Sonnets of Michelangelo together at the Wigmore Hall in London (Britten was an excellent pianist), and then recorded them for EMI, their first recording together.