It has been a turbulent last 12 months for the third in line to the throne with Prince Harry being in the public eye for many of the wrong reasons. But, as the Prince turns 21 tomorrow there are signs the royal wild child may at last be calming down. Nick Morrison reports.

PERHAPS it's no bad thing, given the sparks that seem to fly whenever the words Prince Harry and party are in the same room, that celebrations for his 21st birthday will be somewhat muted. After spending the day itself, tomorrow, at Sandhurst, where he is a third of the way through his officer training, he has been limited to a low-key gathering of family and close friends.

Harry is said to be frustrated at being banned from throwing a wild party, but Prince Charles has good reason to be cautious. Not only has his youngest son developed something of a reputation as a playboy, but the lavish celebrations for Prince William's 21st, gatecrashed by "comedy terrorist" Aaron Barschak who evaded royal security and got close enough to kiss the prince on both cheeks, were embarrassment enough.

Not that Harry missed out altogether. Last week he flew to Botswana and partied on a houseboat with girlfriend Chelsy Davy and 14 of their friends, but once back in England the image will be more subdued.

And this is no more than Harry needs, after a year when he seemed to cement his reputation as a frivolous and feckless playboy. A gap year was stretched to nearly two, and much of it seemed to be spent with a lager can in one hand and a cigarette in the other. Episodes of work - in the Australian Outback and the South American pampas - were cut short, by complaints of Press intrusion and then injury, respectively.

No sooner had he returned to Britain than he was pictured throwing a punch at a photographer outside a nightclub, face contorted with rage. Then came the allegations he had cheated in his art A-level, and finally, and most infamously, the Nazi outfit he chose for a Natives and Colonials fancy dress party.

It was against this background that his arrival at Sandhurst earlier this year was seen not just as giving the third in line to the throne a career, but also helping keep him out of trouble. And so far it seems to be working, with the only flutter a breach of security when a newspaper reporter gained access to the military base and apparently came within touching distance of the prince.

Much of Harry's off-the-rails behaviour has been put down to his circumstances: the death of his mother when he was not yet 13, a distant father who seemed to play little part in disciplining his children, and his position as the "spare". While William seems to be taking his responsibilities as a future king seriously, deprived of those responsibilities, the temptation for Harry is to become irresponsible.

There are those who hope that Harry's military service will be the making of him, in the same way that his uncle Prince Andrew went from being a playboy prince to a Falklands hero. Although there have been rumours that he found the early training at Sandhurst hard, it may be that a military life will suit him down to the ground, says royal watcher Anita Atkinson.

"The last 12 months have been really difficult for him, but the last couple of months he has not been hitting the headlines so much, because he has got his head down," she says. "He seems to be an action man, he loves sport, and I'm sure he will enjoy it in the services. He has just got to prove himself."

Mrs Atkinson, from Crook, County Durham, and listed in the Guinness Book of Records for having the largest collection of royal memorabilia, says the historical function of the armed forces in giving a meaningful role to royal princes could be particularly useful for Harry.

But if the first five weeks were gruelling, they may also have toughened him up and given him a new perspective, away from the partying and polo-playing set which had previously preoccupied him. There were signs of a desire not just to be known for his night-time exploits when he spoke earlier in the year of wanting to follow in his mother's footsteps, as he worked with Aids' victims in Lesotho, forming part of an attempt to create a new image.

To mark his birthday, Harry will give an interview to Sky, and early reports suggested he was keen to talk about aspects of his private life, including his relationship with Ms Davy. He is also said to be eager to set the record straight about his Sandhurst training, in an interview seen as a snub to the BBC, after a Panorama programme suggested the marriage of Prince Charles and Camilla Parker Bowles may have been illegal.

But, to some extent, the image rebuilding may even be unnecessary. Although Harry's drinking and brawling may get him some very unflattering headlines, they also give him a connection with his grandmother's subjects in a way Charles has never been able to manage, according to Mrs Atkinson.

"He is a typical young lad, wanting to have a good time, and he is no different to anyone else except the cameras are on him every day," she says. "I think it is good for the Royal Family, in as much as young people can recognise themselves in him.

"The Royal Family has to adapt and modernise and fit in with the way people are. Princess Anne wore mini skirts in the 1960s - she may have looked awful but it mirrored what young people were wearing, and that's something Prince Charles has never really done."

Although Harry's wild child behaviour may not be appropriate in the heir to the throne, as a heir's younger brother he is in a similar position to Princess Margaret. Her frequenting of nightclubs in the 1950s and 1960s may have scandalised the court, but they also helped maintain a sense of fun, and hence an interest, in the Royal Family. "They can't be too staid, always standing around in long coats, otherwise we would lose interest in the next generation," says Mrs Atkinson. "Young people see that Harry is one of them, he is just fun-loving.

"The day the papers aren't interested is the day the Queen should really start worrying, and Harry is keeping them in the public eye. It keeps people talking about them, and as long as he doesn't do anything evil and is just mischievous, then we can enjoy it."