If you have just moved house and redecorated, moved into a brand-new flat or put in a new kitchen, look about you now. Take in the beautifully draped curtains, the immaculate mantelpiece, the carefully ordered bookshelves. Focus on the pristine kitchen worktops, the ranged knives, the gleaming hob. Memorise your colour-coded towels. Remember it all. Because this state of affairs will not last.

When we finished transforming our house, which had been three derelict flats, into one entity, it was immaculate. Perfect in every way. The day the painters moved out, a friend advised us to take photos of every room, because, she told us, it would never look this way again. She was right. A week later, a child walked slowly downstairs from top to bottom with a blue felt-tip pen pressed to the wall.

From then on, it was a steady decline. Hard as we tried, the towels in the bathroom were never folded into neat triangles again, the artfully arranged photographs in the living room became dusty and disarranged, and the gleaming Bulthaup kitchen never regained the poise of its first six months. Now, the central island is always cluttered, the drawers are always half open, the steel sink is scratched and despoiled with a sprinkling of tea leaves and strands of spaghetti. Admittedly, the kitchen sometimes approaches its former glory when it is blitzed prior to a posh dinner party, but the dog’s scuff marks on the walls always give the game away.

The phenomenon we have been experiencing is house entropy: no matter how vigilant you are with the Mr Muscle, your home will always be verging on a state of chaos, dust and muddle. The minute you redecorate a room, move the furniture around or even wipe down a table top, house entropy will begin, slowly but surely, to undo all your hard work.

Insisting that your house must always look as if it came out of an interiors magazine is like trying to push back the oncoming tide of the sea: an unnatural contest you will never win. House entropy is insidious, almost as impossible to spot as its brother in arms, shelf blindness. Over a matter of weeks, a tidy shelf, mantelpiece or windowsill will unpick your efforts to arrange it voguishly with scented candles and orchids. It will develop an entropic state all of its own, involving balls of dust, chewing-gum wrappers and old coffee cups.

Somehow, you do not notice this. You continue lighting your candles, watering your orchids and thinking your shelf is the height of elegance. That is, until you are about to have friends for supper, at which point the scales fall from your eyes and you look at it with horror. It will take all of three minutes to tidy it up and restore it to its default setting, but unless you know you have people coming round, these three minutes can somehow never be found. So you continue muddling along with everything looking just a bit below par, like a fashionable skirt with the hem trailing.

The older you become, the worse it gets. I say this only because my parents have told me so. They are fit, healthy and active, and their house is charming and elegant, with beautiful silk curtains, polished antiques and a garden worthy of entry into the National Gardens Scheme’s Yellow Book. There are some areas, however, to which they pay absolutely no attention. “We have mould growing up one of the walls in the washroom,” my mother shrugs. “I don’t know why we haven’t got round to sorting it out. We just haven’t. When you take your coats down from the hooks, flakes of plaster come off with them.” My father puts it a different way. “The more your age increases,” he says, “the higher your threshold of tolerance gets.”

So, when should you really buck up and make sure your house follows your desire for order, not its own wish for decline and fall? Everyone seems to have their own tipping point. “When the paint is peeling off the windowsills outside,” my mother declares. “When the carpet is threadbare,” my father says. “When the ingress of damp is larger than a handprint,” Mr Millard opines. “When you can’t put a freshly drained cup of coffee on the mantelpiece because it is so cluttered with old postcards, hair brushes, Biros and other drained mugs of coffee,” my sister says.

There are two ways to cope: you can range all your defences against your house’s wish to end up in a mess, either by getting up an hour earlier every day and cleaning it yourself or by hiring a daily cleaner and organising a monthly delivery of interior glossies. Or you can concede an edgy stalemate, with forays into painting and decorating, ante-dinner-party blitzes and the occasional chucking out of cuddly toys, old Christmas cards and paperbacks that are never going to be read again. After which, you can relax and allow your house to resume its descent into chaos. I know which option I would choose.

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