Photos of Prince Harry naked during a reported game of strip billiards - published on a US gossip website - have been defended as being merely "letting off steam". So how normal is it for young people to take their clothes off when they have been drinking?

There's been a big debate over whether British newspapers should be allowed to show the images of the prince naked in a Las Vegas hotel room, reportedly with a group of women.

Prince Harry is about to enter the next stage of his military career, and some observers have suggested that partying in this way on leave is entirely reasonable.

Many believe he should be entitled to his privacy and say his behaviour is normal for somebody of his age - 28 in a month's time. The prince was in a private place - albeit in front of strangers - and not breaking any law.

The prince was just behaving like a typical young British man, says Kate Fox, a social anthropologist at the Social Issues Research Centre, which has done research for both the government and the drinks industry.

Most people return home at the end of the night fully clothed, they're not missing a cardigan or a shoe and certainly not any trousers or pants Piers Hernu, Men's magazine journalist

"He was behaving perfectly normally. It wasn't in public and he didn't know he was being filmed," she says.

"It does seem to be common, particularly among people who do difficult and dangerous work, like soldiers and medical students, who normally have to be in such control of their behaviour."

Anybody who has been out in a British city around 02:00 on a Friday or Saturday will be aware that there are some people who respond to alcohol consumption by "mooning" or otherwise removing clothing - something which can potentially lead to arrest.

Fox espouses a theory that it's the British and American attitude to alcohol that is to blame for disinhibited behaviour, rather than the chemical reactions of alcohol in the body.

"We Brits believe that alcohol has magical powers, that it causes us to shed our inhibitions and become aggressive, promiscuous, disorderly and even violent," she says. "Studies show that when people think they are drinking alcohol, they behave according to their cultural beliefs about the behavioural effects of alcohol.

"It provides the perfect excuse, because people can blame their behaviour on the drink. They can say, 'It was the drink talking' or 'I was not myself'."

It's that loss of inhibitions that Dr Glenn Wilson, who is a professor of psychology at Gresham College in London, says is the main function of social drinking.

Image caption It is common to see inhibitions break down after drinking

The nudity, he says, "all feels a bit naughty, a deliberate breach of taboo. Some people will have a drink or a cigarette because it seems like a slightly naughty thing to do. I would put this in that category.

"The idea is that you're more vulnerable, it's all upfront and barriers are down. There's some sense that you're more open and connected with people."

And like nervous theatre actors are told to imagine the audience naked, Wilson says nudity also helps break down barriers and disarm people.

Far from being a moral collapse, Wilson says that the prince's behaviour is pretty much keeping in character.

"It implies they are more extroverted and a relaxed kind of person - the opposite to uptight. It does display an extrovert trait in Harry but I think we all knew that about him anyway."

But while Fox argues that getting naked in front of other people after drinking is not an uncommon thing among young British men, freelance men's magazine journalist Piers Hernu disagrees.

"It's quite unusual," he says. "Most people return home at the end of the night fully clothed, they're not missing a cardigan or a shoe and certainly not any trousers or pants.

"Even if they can't remember anything, they normally have their clothes. The human instinct is to remain clothed.

"When we're drunk, bad ideas seem quite good - there's definitely a loss of quality control."