On All Things Considered this week, Roy Jenkins' guest is a world-famous Christian mission pioneer. As a schoolboy of 12, George Verwer started his own business in New Jersey. At 16, he had 200 people working for him part-time selling fire extinguishers, and he also ran a stamp collecting enterprise. Typical beginnings for many an entrepreneur. But George Verwer's direction changed dramatically after he responded to the preaching of Billy Graham. The zeal which had gone into moving fire extinguishers was transferred into distributing Christian literature. Still in his teens, he went to Mexico with a couple of friends to give away gospels, and that trip was to mark the inauspicious beginning of what has become one of the world's largest Christian mission movements. Sixty years on, Operation Mobilisation has 6,000 workers of more than 100 nationalities working in as many countries. Its latest ship, Logos Hope, is the world's largest floating bookshop.