It is ever-cheering to be told that life begins at 40, especially if you happen to be a 39½-year-old with one eye on the calendar. It is, therefore, with particular interest that I pass on to you the glad tidings that it’s not just life that begins — sex does too, apparently.

Sex in your twenties is just confused, exploratory fumbling, according to a survey last week. Sex in your thirties is often hampered by young children waking up three times a night and wanting a chat/drink/wee (or all three). Sex after 40, however, is apparently the bee’s knees.

Which is obviously good news, considering it was only a few decades ago that outsiders saw middle-aged women as granny material — handy if you wanted a knitted jumper or a bowl of stew in a hurry, but not exactly your first port of call for hot bedroom tips.

All that has changed, according to a survey in Good Housekeeping magazine (an improbably frisky publication that recently made headlines by applying its famously stringent Good Housekeeping Institute test procedures to sex toys. Sex toys crop up again in the survey: 41% of over-forties use them, we’re told). Anyway, according to the magazine’s research, more than half of women in their forties are having better sex now than they did in their twenties, with more than two-thirds giving their sex lives a rating of seven out of 10.

Reasons suggested for this renaissance are a) having the self-confidence to know what they want and b) empty-nest syndrome — the removal of grown-up children leading to a resurgence of friskiness; and b is possible only because of c), our obsession with health and fitness, which means that d) middle-aged women today don’t necessarily look as middle-aged as they might.

While I’m pleased about this, I can’t help but feel sad about it, too: I had always looked forward to being quite decrepit in middle age, which I’d thought was when you were allowed to “let yourself go”. There’s something rather enticing about the idea of embracing the kaftan, wearing really big pants, lying on sofas having thirds and so on.

Alas, what with Botox and facial peels and yoga, I expect my dream of middle age will have to be pushed back to when I’m roughly 75, except that by then 75 will be the new 40 and some of us will feel extremely cheated.

Actually, you could argue that while it is, of course, an excellent thing that middle-aged women should feel they are having the best sex of their lives, these findings could also be taken as evidence that our obsession with sex and youthfulness is so great that nobody is allowed to be old any more; everyone must be seen as a frenetically active sexual being first — like tantric sex queen Trudie Styler — and never mind about anything else.

Indeed, being frenetically sexually active is what defines them. Presumably, middle-aged women having good sex as a result of knowing what they want is not an entirely new phenomenon — at a rough guess I’d say it was about 2,000 years old. I’m no expert, but I labour under the impression that most middle-aged couples I know have plenty of sex, just not necessarily with each other.

What is new, though, is the idea that their activity should be celebrated as yet another indication of the fact that there’s no such thing as middle age, only middle youth. After a while it begins to look a bit chippy and defensive and weird.

Nobody shouts from the rooftops about how nice it is to take up gardening, or to suddenly find oneself passionately attached to Radio 4 (or blissful Radio 7), or finally to discover a really fail-proof way of ensuring that your roast potatoes are crunchy and squishy at the same time. We’re only allowed to brag about sex — which is problematic because, as a rule, the people who brag about it aren’t getting any.

I have some difficulty with all of this, because actually getting older is rather nice and because at some point in the past decade I became old-fashioned enough to think “oh, shush” when older women bang on about the fabulous sex they are having — which they do a lot despite, or because of, the current crop being of the 1960s/1970s femmo-vintage.

The former editor of Cosmopolitan magazine, upon hearing of the survey last week, felt moved to write roughly 1,500 words for a tabloid newspaper about how deeply sexually satisfied she is in her fifties which, while being delightful for her, might also be seen as a surfeit of information, as well as no information at all: is having sex all that she does? Is it all that matters?

As for women being well preserved — well, yes, very nice. But one might have hoped that one of the benefits of middle age might be a reduction in the amount of hours a day a woman might spend prettifying herself: with growing self- esteem you might expect a falling away of the desperate need to keep up with reductive definitions of what constitutes attractiveness. Instead, many women step their already punishing regimes up a gear, believing that sexiness means being able to pass for 10 years younger, at least from the back.

Here are some of the things about entering my forties which I am looking forward to — in addition, naturally, to superlative rolls in the hay: the aforementioned roast potato nirvana; more pottering; being curled up with a book instead of racing around boring parties; cooking more; siestas; being picky and not saying yes to everything; not feeling I need three glasses of white wine and 10 cigarettes to enjoy evenings out; going to the opera more often; going for bracing walks.

Granted, none of these things is terribly sexy. To me, though, they are still a great deal sexier than saying, “The absolutely only thing about middle age I’m looking forward to is my sex life.”

I do see that the survey will have cheered any women hovering on the brink of 40 who are, for reasons best known to themselves, panicking about their libidos. But to cheer up middle-aged women as a whole, it might be an idea to allow them to be themselves and not to reduce all their hopes and ambitions to a banal little rating in the bedroom.

• Poor old Jacques Chirac. First he gets it spectacularly wrong about British food, then he goes and loses the Olympics.

  In between, he allegedly found time to slander Finnish food, too, despite having feasted on venison, fish and reindeer at a 1999 dinner with Martti Ahtisaari, the then president.

  I hate gastro-snobbism, especially when the country under attack produces food that is both the definition of poetic (cloudberries) and delicious (cured fish, mashed potatoes, meatballs, lots of salmon). Admittedly, elk and reindeer can be found on the menu, too, but then a nation that eats vast quantities of horsemeat isn’t really in a position to comment on the oddness or otherwise of eating unusual quadrupeds.

  It is so provincial to slag off other countries’ food on the depressing grounds that it is “foreign” and therefore horrible. Even the Brits don’t do that any more.