'He plays the piano well, ' wrote the society hostess Mme de Saint-Marceaux in her diary on 18 March 1927. 'His compositions are not devoid of talent but he's not a genius, and I'm afraid he thinks he is.' Intelligent though the lady was, she got this one spectacularly wrong. Poulenc has in fact outpaced his colleagues in Les Six by many a mile, as singers and instrumentalists all over the world will attest, and while he would never have accepted...