Children run happily along the beach naked, but when their parents take off all their clothes they are nude. The two states are exactly the same — and yet the words used to describe them say very different things.

The first is about innocence. The second is about, if not experience, then certainly an awareness of the effect unclothed flesh can have on the onlooker. It is the story of the fall of man in the Old Testament — Eve, blissfully oblivious to her nakedness, takes one bite of the apple and an irreversible self-consciousness descends. It is the onset of puberty, when children are suddenly aware of their body as never before.

Clothing is so much a part of us that it has become a second skin. When we have to reveal our body, we immediately feel vulnerable, exposed and uneasy. It’s a psychological hang-up that’s very difficult to kill, which is why even those who opt for naturism, or just a few daring hours on a nudist beach, often betray an almost childish defiance.

The need to cover any part of the body that has even the slightest sexual connotation runs deep in the soul, even though children show just how artificial this is. Why do we feel that we need warnings as we approach a nudist beach? Do we really think that we — or our children — will be traumatised by a glimpse of other people’s bits and pieces?

The authorities clearly think so, which is why so many of them made fools of themselves during one man’s naked walk from Land’s End to John o’Groats last year. Normal, well-adjusted people were as much amused as bemused by his decision to walk the length of Britain without clothes. Their reactions proved that behind the prudish moral attitudes sits a little-known truth: the Brits think getting naked is really rather fun.

Times recommends

• Who killed Jade Goody?
• Daisy Goodwin: This is better than real sex
• Are eldest children really a cut above?