Capturing 1960s music icons from jazz clubs to Woodstock

You may not know the name Jim Marshall, but you probably know his photographs. His collection of work is a near-complete account of the cultural revolution that took place in the 1960's, from jazz clubs to Woodstock. Now, his long-time assistant, Amelia Davis, is trying to promote his work and alter the way the world thinks about the legendary photographer. Christopher Booker has the story.