Petroc Trelawny presents the second part of the First Night of the 2009 BBC Proms, as sisters Katia and Marielle Labeque kick off the season's focus on works for multiple pianos with Poulenc's Concerto. Katia and Marielle Labeque (pianos) BBC Symphony Orchestra Jiri Belohlavek (conductor) Poulenc: Concerto for two pianos.