By George Pierpoint BBC News Image source, Getty Images This summer marks 50 years since 400,000 people flocked to a field in upstate New York for "an Aquarian explosion" of "peace and music". The Woodstock music festival, held at a farm in Bethel, has come to symbolise much of the idealism of the 1960s. It is seen by many as the nexus of freedom, sex, drugs and rock 'n' roll which fuelled the countercultural movement of the decade.