We didn't know where it was all going. We just didn't know. One day in September 1968 Don McCullin, then regarded as the world's most accomplished war photographer, received a commission from the Apple Corporation to spend a day photographing the Beatles. McCullin had just returned from covering the bitter fighting during the Tet Offensive in Vietnam, and was the most hardened photojournalist in the field. He was astonished by the invitation. On Sunday 28 July he met the Beatles at the Sunday Times studio and began to photograph them in colour for a Life magazine cover. The day that followed has become known in Beatles lore as 'The Mad Day Out'. McCullin shot twenty rolls of black-and-white film in various locations across London, from the banks of the Thames to Paul McCartney's garden. Apart from the cover photograph and two pictures in McCullin's recent book In England, we believe the work to be otherwise unpublished. The timing of this day was significant. At the height of their international fame following the release of Sgt. Pepper's Lonely Hearts Club Band, the Beatles were in the middle of recording the White Album. The war was raging in Vietnam and riots had spread through capital cities worldwide. It was the very moment of a generational divide, and the Beatles were the iconic figureheads of the youth movement. One of the most poignant photographs taken that day was of John Lennon posing as dead, surrounded by the other three, in an image that he himself had carefully choreographed. What was an intentional pose in protest is now seen as tragic and prophetic. These pictures are of four inspired musicians on the cusp of the change. They mark the passing of an era in which we can glimpse our own lost youth.