Historian Amanda Vickery and broadcaster Tom Service unearth the fascinating story of the life-long friendship between composers Ralph Vaughan Williams and Gustav Holst, whose music gave birth to the 'English sound' in the first half of the 20th century. They retrace the walking trips the two composers took together across the country to discover how influences ranging from the Renaissance masters to folk music imbued their music with the 'Englishness' we recognise today.