Tom Service investigates what happens when musical rhythm gets stretched or loosened. What is going on when a jazz band makes a tune swing, or a Viennese orchestra makes a waltz swirl? Liberties are taken with strict musical time in order to add expression and excitement - but you have to have the knack. He also consults pianist Stephen Hough about how to play Chopin and Rachmaninov with authentic flexibility. So whether it's Count Basie's Band or the Vienna Philharmonic, Tom unlocks the secrets of rubato.