The law, in the UK, regarding nudity in public is complex and, although not in itself illegal, there are laws that could be and have been in the past used against Naturists.
Below is a link to guidance issued recently to the Police by the Crown Prosecution Service. It is well worth reading and it could save you a lot of trouble. Its existence is also something that you should remember, should you find yourself wrongly accused of an offence involving nudity.
Noah's Ark does not condone reckless public nudity but we should all remember that events such as the World Naked Bike Ride are allowed to continue without any police interference
Please click the image below to access the whole document