Dr Starkey reveals why Henry V took a choir with him to the Battle of Agincourt, and hears the music the king wrote to keep God on-side in his crusade against the French - rarely performed in the centuries since, and now sung by the choir at Canterbury Cathedral. He visits Eton College, founded by Henry VI, where today's choristers sing from a hand-illuminated choir book which would have been used by their 16th-century predecessors, King's College, Cambridge, built by successive generations of monarchs and still world-famous for its choir, and the Chapel Royal at Hampton Court Palace, where Henry VIII and Elizabeth I heard works created especially for their worship by some of the greatest composers in British history.