There are now 12,000 registered members in nudist clubs in Britain today-their numbers are on the increase. And the number of clubs catering for them has nearly doubled in the past five years; clubs where they can pitch their tents, park their caravans, or just take off their clothes. The fantasy is familiar: the sea, the sand, and a body tanned by the blazing sun; but reality lies a . good distance off. Nudism in this country is more likely to mean a wet weekend in Cheshire or a chilly day near St. Albans. But die-hard nudists are not easy to deter. They come in all shapes and sizes. Some families even live permanently in nudist colonies. This summer more applications than ever before have been made by groups of nudists to use beaches and swimming pools to prove their point. Exercise keeps the cold out. If it rains we don't spoil our clothes, the argument runs. If it snows you can always keep your Wellingtons on. What sort of people are they? What is the life they believe in so passionately? In nudist resorts and at a nudist hotel Man Alive takes a frank look at the people who mean it when they say ' Take off your clothes and live.'