TO hear a ring on the doorbell and find one of Jehovah’s witnesses standing on the doorstep is now part of the pattern of modern life in Britain. Their giant conventions, conflicts with authority, gruesome stories of concentration- and labour-camp sufferings, legal battles and unusual views often bring them into the headlines here. Whether or not one agrees with their doorstep-religion methods, it is difficult to ignore the group. What are they trying to do? What sort of people are they to get into so much trouble? Exactly who is running them and who is financing them?