If cleanliness is next to godliness (which I doubt), then the following should also be true: the more you boast about it, the more suspect you are. I’m amazed by the number of people who insist on telling me they take two showers a day, as if they’re the Mother Teresa of personal hygiene. What manner of grime are they washing away? It’s hard not to think of Lady Macbeth’s frenzied attempts to scrub the blood from her hands. So when I read of a survey that stated 4 out of 5 British women don’t shower every day, I applauded our common sense. If you live in a cold climate, aren’t a fishmonger and do little more arduous of a day than pop to Sainsbury’s, why waste all that water? As my granny would say, “You’re just scrubbing off all your essential oils and replacing them with muck.”

The compilers of the survey, however, seemed scandalised. And horrified by the admission from two thirds of women that they tumble in to bed with their faces still slap-coated. The reaction is hardly surprising, when you realise the data was collated on behalf of the skincare range Flint + Flint. Manufacturers of unguents can’t flourish unless womankind is in a constant state of malodorous paranoia: lathering, toning and moisturising every last inch of their epidermis. Stubborn slatterns like me can halve their profits in an instant by simply going on soap strike.

But being grubby and proud is part of a British woman’s heritage. We are internationally famed for our insanitary ways. I was a guest once at a dinner party in California where the hostess was deploring the personal hygiene of her son’s latest girlfriend. At which point a friend said gallantly, “She can’t be worse than Rowan – she once went a week without bathing.” The hostess replied serenely, “That’s different. British women are always dirty. They spend too much time with dogs and country houses don’t have hot water, or en suites.”

This was certainly true of my childhood. Our little cottage adjoined my parents’ pub and housed five children, two dogs, two cats and a guinea-pig and we only had one bathroom. The Aga heated the water and could barely fill one full tub. We bathed in order of age once weekly and I always slipped into a lukewarm soup of grey Palmolive scum and a half-sodden towel after. At least this was preferable to the freezing cold showers my husband endured every morning at his character-forming boarding school.

You may begin to understand why my household doesn’t fetishise daily ablutions. My sons are hosed down vigorously when necessary, but I’ve never held with this every-night bathing tyranny. Forty minutes’ tumbling, tickling and storytelling seems more important to me. We bought a shower unit for the new bathroom when our loft was converted, but could never quite summon the willpower to have it installed. It lent against the wall for two years and then I gave it to my sister.

I still prefer a good old-fashioned bath, even if it takes me a couple of days to get round to the ritual – which involves piping hot water, a book, a glass of Scotch and a long soak.

The daily over-rinsing lark is just another form of one-up-woman-ship. It indicates that you have your central heating turned up high enough that you can waft in and out of a shower several times a day without contracting hypothermia. It also suggests you’re having so much red-hot sex with your adoring hubby, that you have to be perma-fresh for his attentions. These scruboholics make you feel slovenly just by lounging next to you in their white linen T-shirts. At such moments, I restore balance to the universe by recalling this line from Great Expectations: “Mrs Joe was a very clean housekeeper, but had an exquisite art of making her cleanliness more uncomfortable and unacceptable than dirt itself.” A little grime can be becoming in a woman.