Oxford University Cave Club
David Monaghan's experience took place in 2/7.
He was passing the rebelay on Pessimists, which is a 70m free-hang. Instead of clipping in his cowstails, he clipped in the harness-end of his footloops and then proceeded to take his jammers off the rope! That doesn't leave many points of attachment.
David's other name, by the way, is "safe caver".