Philip Hensher: The Army is the right place for William

It was a great mistake to send him to Eton. It ran the risk of turning the future king into a posh boy

Prince William arrived at Sandhurst at the weekend to begin his officer training. As heir presumptive to the throne, he was spared the traditional indignity of carrying in his own ironing board - that was carried in via a back entrance by some equerry or other. However, we are told with some enjoyable frisson, he will be called Wales, be treated like any other officer cadet and yelled at by sergeant majors - though the one who used to shout "You're an idle little king, sah" at the late King of Jordan must be retired by now.

He will be given the standard haircut - something which, judging by yesterday's photographs, he has been putting off for a week or two (one likes to see the signs of the traditional Windsor carefulness over money emerging). Best of all, he will have to call his younger brother, who went to Sandhurst some time ago, "sir" when Harry becomes an officer.

The whole idea of the next king but one being sent to Sandhurst for military training seems terribly old-fashioned; something inflicted on the sons of George V which might not be awfully appropriate any more. Certainly Prince William doesn't give off much of an air of innate military bearing, and his education - surprisingly good A-levels and a sloaney degree beginning with Art History and ending with Geography at St Andrews - doesn't suggest anyone obviously suited, in traditional ways, to Sandhurst.

At a time when we have little time for the requirements of duty, and tend to think that anyone ought to pursue their talents in ways which suit them best, Prince William's decision to go to Sandhurst, if that is what it is, may seem not just old-fashioned but unfortunate. Bearing in mind that the last member of the Royal Family to enter the military, the Earl of Wessex, left under a cloud of whingeing, and it doesn't seem to have been seriously considered for, say, the children of the Princess Royal, one might have thought that the military career, even for a future king, was less obligatory than once it was.

The Prince of Wales's household has certainly been at pains to set William up with a wider range of experience than he might once have been offered, even if these have not always been as profound as was suggested. A stay in Belize after leaving Eton "involved sleeping in a hammock strung between trees, wearing jungle combats, hats and boots, and eating British Army rations", and afterwards a visit to an educational project.

There has been a spell of voluntary work in southern Chile, and, last autumn, three weeks of "work experience" in the City. It was "organised by leading bank HSBC, [and] included visits to a number of the City of London's iconic financial institutions including the Bank of England, the London Stock Exchange, Lloyd's of London and even Billingsgate Fish Market". Is that a financial institution? Never mind - I'm sure something interesting sunk in.

It may not seem all that important, how the next-but-one spends his formative years. But in reality, the interests and occupations of someone who is going to occupy the nominal but conspicuous role of head of state are of great importance to the national psyche. They can't simply be upper class, or society figures - in fact, few successful English monarchs have ever been describable as leaders of society, though some of the very worst have been happy with that role.

They have to embody, from the start, something of national, rather than social importance. For that reason I think it was a great mistake to send Prince William to Eton; someone in that position should not confer any social cachet on, or derive any from such an institution. It ran the risk of turning a future king into a posh boy, something which kings should never be. Indeed, "society" in the usual sense has always rather sneered at the greatest of monarchs, and laughed afterwards at the frightful dim tedium of a week at Balmoral with Queen Victoria.

For those reasons, I rather think Prince William's three weeks in the City with a lot of red-braced money-movers inadvisable; inadvisable, too, those posh-boy jaunts on behalf of charity to southern Chile and so on. Both are exactly what you would expect an Old Etonian to be doing.

But going into the Army is a very good thing. Not because Sandhurst offers any more democratic an occupation, but because it can be firmly acquitted of any flavour of fashion or worthiness. Future kings have always gone into the Army or the Navy; it is simply their habit, and their duty as future heads of the armed forces.

These days, it is rather the thing to think of the armed forces as yet another career option, like going into Lloyd's or becoming an estate agent. But that is exactly what it is not. Dr Johnson said that every man thinks meanly of himself for not having been a soldier, and I can't help feeling that the dignity even of a direct heir to the throne is enhanced by this service. It is psychologically connected to the spine of the nation in a way that HSBC isn't, and I think we want a future king to have some direct history with it.

If you doubt that, just take a look at the Royal Family, the next time they turn out en masse for a funeral or a wedding; if most of them look splendidly dignified in their uniforms and - admittedly, rather easily earned - medals, you would rather not be the poor old Earl of Wessex even in the most exquisitely cut of frock coats. Yes, Dr Johnson was right; and I don't think we would want Prince William to excuse himself from what goes on being a national duty.