In the end, the lure of celebrity proved just too much. The arrival of the diffident 27-year-old Old Etonian, who might conceivably one day become their monarch, provoked sneers in Australia before he touched down on Tuesday. But by Thursday, he had been transformed from Willy the Wombat into — according to the tabloid Herald Sun — a Dinkum Aussie Larrikin. You could go a long way through the Outback to find someone less like a larrikin (which usually translates as a bit of a hoodlum), but that's what the presence of royalty can do for you.

Many thousands turned out to see the prince in Australia and in New Zealand earlier in the week. Outside the new Supreme Court building in Wellington, which William had been sent to open on behalf of his grandmother, people greeted him with cheers and worried about the effect of the sun on his bald spot. Maoris beamed with pleasure that the grandson of the Great White Heron had come amongst them.

In Sydney, Aborigines who spend their lives crammed into a dismal slum area called the Block came out in thousands to welcome a young man as different from them as it is possible to imagine. William's gay fanbase turned out in "I Love Willy" T-shirts.

And he did not disappoint. Like his mother before him, William hugged babies in hospital wards and spontaneously put his arms around elderly Aboriginal ladies. He listened gravely to survivors of last February's devastating Victoria bushfires. He joshed the parachute squaddies of the 3rd battalion Royal Australian Regiment on their firing range, where his shooting proficiency provoked genuine admiration.

So, as he and his advisers flew back home - business class on a scheduled flight, not by private jet like some royals - they will undoubtedly feel buoyed up by success. They may even have been chortling gently that the pro-republican Melbourne Age noted yesterday, under the headline "All-round Good Egg William Snares Many with his Charm Offensive," that the prince "may have done more to set back the republican cause than anything since the 1999 referendum" - which, of course, the republicans narrowly lost.

That is good news indeed for Buckingham Palace and, across the road, Clarence House, home of William's father Prince Charles. Because William is the best hope they have.

Things are looking bleak for the monarchy right now. There isn't much stardust around for the foreseeable future: the Queen is approaching her mid-80s and, with no sign of ill health, may be good for another decade or (if she has inherited her mother's longevity) two. Her famously grumpy heir, Charles, is now 61; he will already be an old man when he inherits. So it is to the next generation the family must turn, even though William, already approaching his 30s, will probably be middle-aged by the time he is crowned.

All the more reason, therefore, to pay attention to the prince's progress as he finally, by taking on grown-up engagements of this sort, begins to take the burden off the oldsters. This week was the first time that he has undertaken an official overseas tour (at least so far as the New Zealand leg of the trip was concerned) and, as fate would have it, it was to two countries that have been murmuring for years about dispensing with the monarch and having their own home-grown head of state.

No wonder then that accompanying the prince was a small, elite team whose job it was to keep him from gaffes and pitfalls. Major Jamie Lowther-Pinkerton, the leathery, hatchet-faced former SAS man who is the prince's private secretary, was to be seen alongside him, glowering as he was handed yet another bouquet of flowers to carry (the flowers having been thrust at the prince during his walkabouts). Beside him, equally discreet, was Sir David Manning, the former diplomat whose career peaked as Tony Blair's foreign affairs adviser and then ambassador to the U.S. during the period after the Iraq war.

There were also three security police, a young press officer and a secretarial assistant, but this was not all: watching beadily from the public seats as William opened the New Zealand Supreme Court was none other than Christopher Geidt, the Queen's private secretary. Clearly uncomfortable at being spotted, he protested that he had only dropped by because he happened to be in Wellington: "I am just on holiday and it was suggested I might like to look in."

What all these helpers, official or otherwise, will have reported back to senior royals was how well William did. He was charming, empathetic, approachable and informal. He smiled and told jokes, he listened seriously and engaged with what people told him, he was clearly moved by the victims of the bushfires and he asked serious questions, beyond the "Do you come here often?" that so many of the royals use as a substitute for conversation.

He also wore informal clothes - Asics trainers and cords and open-necked shirts - some of them the same two days running. In short, how unlike the life of his own dear father, who needs a valet on tours and has been known to change suits several times a day.

William even mingled with the press, albeit briefly, in a bar by Auckland harbour. I'd like to tell you what he said but, of course, it was all off the record, though he clearly knew the tabloid correspondents well and enjoyed the game of evading their attentions. Not surprisingly, they like him very much. It would be difficult not to.

And the stardust rubbed off. Here's Ali Williams, towering All Blacks skunk-haired lock forward: "He's got to do what he's got to do - he's only human, isn't he?" And another Ali: Aunty Ali Golding, a 67-year-old Aboriginal woman from the Block who has met the Queen and Princess Anne and showed William photographs to prove it. "You look as though you have met more of my family than I have," he told her. She said afterwards: "I think he's excellent in his mannerisms - a real human being. His spirit was really down-to-earth. He's got the character and spirit of his mother and as long as he exists, she will. I think he would be a most excellent king."

And here is a middle-aged, unshaven chap in vest and shorts, living in a cabin in the outback village of Flowerdale after his house burned down in last year's disastrous bushfire, who said to me: "Look at that - he shook my hand!"

As William flies back, perhaps he will reflect that the royal duty that he speaks about will involve encounters and lobbying and receptions and barbecues and walkabouts and meetings with politicians and governors and Prime Ministers for the rest of his life. It is part of what monarchs do and always have done.

What he will also know is that he will have to endure puerile analysis of everything he does. Then, of course, there will be the endless speculation about if and when he will marry his girlfriend Kate Middleton. "Wait and see," he said airily this week, a remark sufficiently ambiguous to prompt more exegesis.

So what have we learned of Prince William? Well, his taste in music turns out to include Linkin Park and Kanye West; that he believes he has no taste in clothes, though Harry's is worse; that he is a good shot and bad at table tennis (and even worse at Wii tennis); that he can keep a straight bat at cricket. And that his bald spot - the subject of much Australian mirth and New Zealand concern - is growing fast.

We have learned, too, that the public is interested in him and that royalty can still produce fawning. "God bless you William," the Aborigines cried as they queued up to have their photographs taken with him. ("Course you can, my loves," he told them and, lapsing into the demotic, "No worries.")

A palace aide said: "I would not like to say whether we achieved the objective of giving him the chance of getting to know the people of these countries, but he has been incredibly gratified by the welcome he has received. It was a very successful tour and he enjoyed every moment."

Does this turn back the long-term republican tide in Australia and New Zealand? Of course not: even though the impetus is currently lacking, a majority of both populations seems to want republicanism and Australian Prime Minister Kevin Rudd's spokeswoman this week suggested that, if Mr. Rudd's Labour government is re-elected later this year, it will initiate a debate "in due season." The fact is that celebrity and the royal touch will not sway everyone.

As Professor George Williams of New South Wales University and the national committee of the Australian republican movement wrote this week in the Sydney Morning Herald: "Having Prince William as our future king represents a failure, not on his part, but of ourselves." - © Guardian Newspapers Limited, 2010

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