AGE IS JUST A NUMBER

And it means less and less, as our seniors are proving more and more

It’s 9am on a Tuesday and I’m doing an aqua aerobics class with my mum and her mates. There’s a good 40 of them with their neat hair and underwired one-pieces punching out leg raises and bicep curls to Van Halen’s Jump.

Afterwards some stay for coffee while others nip off to collect grandchildren, play nine holes of golf, plan a family meal or head to their part-time jobs. My mum, at 71, still works two days a week.

How this lot laugh: at the expletives in one of the songs the instructor has chosen; at the fact they’ve brought two pairs of knickers but no bra to change into; at another friend diligently walking laps of the pool because she doesn’t like water.

Standing there chest deep in the pool — “the water should come up to your boobs” one tells me — I realise this is what getting older looks like and it’s absolutely brilliant.

Remember when old age was beige? Beige hair (unless you gave into the grey), beige elasticated slacks, a beige sofa, beige meals — because hubby didn’t like fancy risottos and beetroot salads — beige slippers and endless cups of beige tea unless you’d holidayed on “the continent” and returned with a taste for le cafe.

Turns out my mum’s generation has reinvented ageing and instead of armchairs and meatloaf on Tuesdays they’re gadding about on walking holidays in Croatia and wearing purple spectacles and saying “Oh well, could be worse” when utterly horrible things happen that would’ve found their own mothers necking Valium.

These women refuse to see their advancing years as a decline, so they pop on some lippy and blush — cream now, not powder — and crack on as if this is the prize for a lifetime of periods and childbirth and mastitis and the menopause.

They’re flexible, forgiving and funny and — possibly for the first time in their lives — comfortable with who they are. Simone de Beauvoir wrote about “coinciding with yourself”; this lot are at that enviable axis where who they are is what they want to be.

What’s more they have poster girls aplenty. Judi Dench heads up the senior sorority with a self-possession which meant she could virtually play herself in the Marigold Hotel movies. Her character had a job, a purpose and 50 ways with scarfs; she would’ve been fine without the marvellous Bill Nighy, but was open to the notion that life might be rather jolly with him.

Obviously there’s Helen Mirren, Meryl Streep and Susan Sarandon, but also a new generation coming through. France’s new first lady Brigitte Trogneux is all leather pants and well-cut jackets and an “I don’t give a damn” smile. Everyone else may be making a huge deal about her husband being 24 years her junior, but the 64-year-old grandmother of six simply kisses the new President and carries on as if everything is tres normale.

And then there’s those heading towards 60 — Ellen de Generes, 59, Emma Thompson, 58, and Julia Louis Dreyfus, 56 — who are so embedded in our consciousness as thinking, sneaker-wearing iconoclasts that it’s impossible to imagine they’ll ever get properly old.

“Onwards and sideways” appears to be the motto of this generation, who rebranded middle age from a crisis to a passage you travel through to get to that fabulous stage where you’re any day away from an awful ailment so best live it up. I know of one couple in their 80s who travel the world seeing multiple performances of The Ring Cycle simply because they love it, and another in their 70s still skiing each winter, although the wife is a bit miffed she now has to wear a helmet. A friend’s 72-year-old mum pitches reality TV show ideas to one of our foremost production companies — “I mean, they’re terrible but go mum” — while another, also in her 70s, is thinking of cycling the length of New Zealand.

I can’t tell you how comforting this is as I round out my 40s standing in front of the fridge trying to recall why I opened it in the first place. Or I put off getting reading glasses. Or I wonder when I might have to cut my hair short and whether it’s bonkers to spend $100 on a serum that comes in a thimble-sized pot. (Never for the hair, apparently, and an hour of hot yoga works better than any serum).

I’ve glimpsed the secret to late life joy and it’s nothing to do with dressing “appropriately” or following a carb-lite diet or worrying about whether your eyelids are drooping.

It’s not dependent on whether you’re married or divorced or widowed or whether you have your grandkids every Tuesday or refuse because you prefer mahjong. Equally, it’s not about being “invisible”, because you’re not to those who love you and they’re all who really matter.

Thanks to my mum and her aqua aerobics buddies I’ve seen what you need — in short, a cracking attitude and a willingness to laugh like a drain. Thanks for teaching me the moves, ladies.