Jonny Greenwood, Britain's foremost exponent of art-rock, has long acknowledged his debt to the Polish avant-garde master Krzysztof Penderecki. This collaboration is the fruit of a concert in Poland last year. Penderecki's Threnody (1960) still has the power to shock, while Greenwood's Popcorn Superhet Receiver (2005) is already a modern classic. His 48 Responses is as surprising as it is original, taking the one brief moment of tonality in Penderecki's Polymorphia and developing it into a Bach-like chorale that morphs and splinters into a series of brief, hallucinatory movements.