Thomas Sutcliffe: Royal bodies and their stains

There's an intriguing display on the top floor of Kew Palace, just re-opened to the public after a £6.6m restoration project. It simultaneously chastises the visitor's urge to touch and indulges it - reminding you to keep your hands off the fabric of the building but offering three small swatches of paintwork and flock wallpaper on which you can exercise (and possibly exorcise) the tactile impulse. These have been connected to electronic counters so that visitors will have a statistical measure of the speed at which human contact erodes a pristine finish. At about 140 touches, which was the figure the counter had reached when I visited earlier this week, you could already see the first faint signs of distress. The pink of the paintwork was smudged with grey, the pile of the wallpaper visibly thinning.

What life there is in distress, though - and how lifeless perfection can be. The restoration of Kew Palace, an on-and-off home to George III and his family, has been beautifully done, and it's well worth a visit. But, like any grand project of historical reconstruction, it struggles with the deadening effect of fresh paint. Never mind that the paint exactly reconstitutes that scraped from buried layers of decoration. Never mind, too, that the Royal Family might have expected their apartments to be finished to the highest standard. What the unmarked surfaces of Kew Palace tell you is that the occupants are long gone - that no one lives here any more.

The curators of the palace know that perfectly well, of course - and they've taken several steps to counteract the inert gas that seeps into all display houses (historic or commercial) and can so easily suffocate them. As you tour the rooms, for instance, you're accompanied by a "radio play", which - notionally at least - brings to life the former inhabitants, complete with Queen Charlotte's Germanic accent and George's characteristic "What! What!".

In practice, though, this simply adds another layer of perfect finish. What's most obvious is the clarity of the diction and the skill of the sound balance, with its tweeting birds and crunching carriage wheels. Then there are the son-et-lumière projections, casting images of people on to the empty walls and, in one case, ingeniously suggesting that someone is standing at a sunlit window, examining her embroidery. But these, too, have the odd effect of drawing your attention to the emptiness of the space, rather than mitigating it.

What is far more successful is the dirt and the damage. The upper floor of the house has been left stripped back to its architectural bones, a brilliant decision that allows you to see how layered the building is - and how thin the veneer of regal polish is. There's life here - in the fingerprints left by builders in the fresh plaster and in the collage of timber used to make alterations to the 17th-century original. But most vivid of all are two relics of royal mortality that go vividly against the grain of restoration. One of them is the armchair in which Queen Charlotte eventually died - black and battered and worn shiny by use. It looks like an old woman itself, carrying the scars of employment.

The other is George III's silk waistcoat, worn by him toward the end of his life when he was suffering from the porphyria that was wrongly diagnosed as madness. The silk is still bright and the cloth unripped, but it is badly stained. George's physicians complained that he demonstrated a "perverse disposition to uncleanliness" during the more extreme phases of his illness - so it's hard not to imagine the rusty blots and discoloration as spilt food or bodily fluids. "Removing them would remove a vital part of its story," read the press notes on this object - and "vital" is precisely the word. Usually, historical costumes shape a psychological and bodily vacancy, but this one is as vividly personal as the letter from Queen Charlotte in one of the display cases, complaining about the conduct of the king's doctors and blotting the lines in her indignation.

Looking at such objects, you're reminded that what life comes down to is leaving some kind of mark - sometimes deliberated and crafted but more often than not accidental. Kew Palace, for perfectly good reasons, wants to limit the scuffs and smears and scrapes that mere commoners leave behind them - but it is at its most gripping and lively when it shows you that royal bodies exert the same friction. That badge of frailty is what really summons the spirit of the former inhabitants, rather than actors' voices and projected images. It's the human stain - what Philip Roth in the novel of that name celebrated as "life, in all its shameless impurity".