Gershwin called Rhapsody in Blue a "musical kaleidoscope of America, of our vast melting pot, of our unduplicated national pep, of our blues, of our metropolitan madness" – an ideal description of a work which, even now, epitomises the birth of American music, and never mind that by 1924, when he wrote it, plenty existed already. It may come as a surprise to learn he scored it for two pianos, with orchestration provided later by Ferde Grofé. The Labèque sisters give a relaxed, louche, smoky but beautifully lean performance. The West Side Story arrangement, by Irwin Kostal and with percussion, is well done and stylish, if without quite the purity of the Gershwin.