Increasingly, older women like Iris Apfel, Meryl Streep and Hillary Clinton are happy to be upfront about revealing their age. We should take note.
When I was walking the dog one bleary-eyed morning this summer, I caught sight of a familiar-looking woman in a dry cleaner's window. She was on the cusp of 40, a little exhausted-looking, and a tiny bit pudgy round the middle.
It was only when I got home and I had my first cup of coffee of the day that it finally clicked. "Sweet Jesus, that woman in the window was me. Is that what I look like to the rest of the world?" I might feel 25 inside, but my exterior begs to differ.
I turned 39 yesterday. It's no milestone birthday but old enough for waiters to start calling me ma'am. I'm not thrilled about my age but I've never lied about it (well, not since I was 16 and trying to score a bottle of Ritz in the local pub). And I don't intend to start.
In some circles, it's considered bad manners to ask a woman how old she is, and there is a grand tradition of older women refusing to even entertain the idea of disclosing their age.
Indeed, Wendy Leigh, an author and biographer of celebrities such as David Bowie, wrote earlier this month about how she hasn't told the truth about her age since she was 30 (Wikipedia alleges she is 64).
Leigh said: "As far as I'm concerned, my real age is no one's business" and that never revealing it is a "liberation", especially romantically - she's dated men ranging in age from 35 to 70.
I think hiding your real age is increasingly becoming an
out-dated concept. I've interviewed hundreds of women over the years for lifestyle features where including the subject's age is obligatory.
Only a handful of those women were coy about their age, politely evading the question. Admittedly, I felt these responses were a little precious. It's not the 1980s and are you not Blanche Devereaux (the man-eater in the Golden Girls who guarded her date of birth like a state secret).
We can't all age like Susan Sarandon, Kim Cattrall or Diane Keaton, nor, as regular women, should it be expected of us; acclaimed actresses work hard at keeping their figure and staying youthful because they regard it as part of a job that commands stratospheric earnings.
Yet we can learn from the way older female role models handle scrutiny of their age. You don't see Helen Mirren (70) getting all skittish whenever someone raises the burning question of her date of birth. Hillary Clinton (67) skillfully deflected observations about how, if elected, she would be the second-oldest American president to take office after Ronald Reagan by joking: "I have one big advantage: I've been colouring my hair for years. You won't see my hair turn white in the White House."
For many women, the epitome of graceful ageing is 66-year-old Meryl Streep, who plays a rocker in the film Ricki and the Flash, which will be released in Irish cinemas next week. When the three-time Oscar winner was asked about celebrities getting plastic surgery to turn back the clock, she said: "I just don't get it. You have to embrace getting older."
But one of the best advertisements of being honest about your age is Iris Apfel, who turns 94 on Friday. The eccentric New York fashion icon, who helped decorate the White House for nine American presidents, is celebrated in a new documentary film called Iris.
"What's wrong with being 72 or 82, or 92?'' she says in the film. "If God is good enough to give you those years, flaunt them. It's ridiculous this idea that once you reach a certain age you are ready for the junk, that being old is somehow dirty and disgusting. The alternative to old is not very pleasant."
In the era of social media, anyone bothered enough to uncover your real age can do some guesswork from your LinkedIn profile or from the digital footprint you leave behind on Facebook.
Besides, not caring about how old you are or what other people think of you are among the true pleasures of getting older. You can trot out the old chestnut "age is nothing but a number" as often as you like, but fooling yourself about your age is a sign of vanity.
I'm no major fan of Oprah Winfrey, but I have to agree with her stance on ageing gracefully. "You are denying your very existence by trying to lie about your age. It's just so silly because you'll continue to age anyway."
It's understandable that women are sensitive about getting older in a society that prizes youth and beauty in women above ability, integrity, humour, wit and kindness (it's not the same for men - just ask George Hook, the 74-year-old broadcaster whose face for radio doesn't stop him from getting hired for TV presenting jobs).
Women on television, in film and in the music industry often feel compelled to lie about their age - their reward for honesty can be unemployment. Actresses Calista Flockhart, Sandra Bullock and Rebel Wilson have all knocked off a few years from their age at one time or another, as has singer Nicole Scherzinger and model Agyness Deyn.
Understandably so; in May, 37-year-old actress Maggie Gyllenhaal revealed that she was turned down for a film role because she was too old to play the love interest of a 55-year-old man.
It's time to stop regarding ageing as some kind of personal failure. Guess what? Even the nubile 22-year-old girl loudly scoffing at a 50-year-old woman for daring to be in the same trendy bar as her is going to be 50 one day too. We're all going to age, and no amount of wheatgrass, Bikram yoga, moisturiser or botox is going to change that.
Women who continue to be vague about their age are merely holding up this falsehood that we reach an expiration date - professionally, socially or romantically - once we hit 40, 50 or 60. Women have a responsibility to each other not to contribute to this.
Just because I don't care whether people know my age doesn't mean I don't constantly fret about getting older. I've been self-conscious about my age since I hit 30.
When I was a fake-ID carrying teenager, 39 was not only ancient; to be that old meant you were a fully fledged responsible grown up with a mortgage, a car, a tidy home, kids, and a proper job and you had a meagre social life that revolved around the odd dinner party.
Now that I'm on the verge of 40, I still show few signs of becoming a real adult. I don't drive and don't care, I have no interest in interior design or DIY, I have a job that requires commuting from the bedroom at 9am to an "office" in my kitchen, and have only ever thrown one dinner party.
I haven't yet given up smoking and even my bedroom resembles that of a teenage girl - the floor is barely visible from clothes and the overnight bag from my last weekend trip has not yet been unpacked. I couldn't care less about the tog of a duvet and never buy an item of clothing that requires ironing.
I regularly buy basil for my windowsill to throw into pasta dishes, but never manage to keep it alive for longer than a week. I still buy skinny jeans in Topshop and I'm not above getting my mother to ring me if I have to get up ridiculously early, 7.30am.
Leigh believes that "the minute you declare your age, assumptions are made about who you are and what you should be doing at that stage in your life". I can only agree with that.
There are plenty of life events that I have failed to mark, primarily getting married and having kids (if my proverbial biological clock ever sounded, I ignored it with the same distaste I have for alarm clocks).
But there are other signs that I am acting my age, not my shoe size. I lose the will to live when I'm in a nightclub where I can't hear myself speak, I've long traded in the bikini for a cosy one-piece swimsuit, rarely wear high heels, and I'm no longer pathologically late for everything.
I may never have kept a plant alive but my Yorkie still seems to be breathing after three years of living with me. Most importantly, I don't give a toss about what people think of my swimsuit or my age.
Oscar Wilde famously wrote that "One should never trust a woman who tells one her real age. A woman who would do that would tell anything".
You know what? I probably would. So shoot me.