Next month I will be twenty-nine. So you know what that means, this time next year... I've spent the last couple of years not really remembering whether I was 26 or 27 or 28 - no worries. But I can see now that this was a kind of sub-conscious avoidance of anno Domini, refusing to acknowledge the GMT of my biological time-clock.

A recent catalogue of events has made me realise, with horror, that lots of people are younger than me. For instance last week I learned that my ex-boss's eighteen year old son was going out with a twenty-eight year old woman who is a model for the artist Lucien Freud. I remember when this sweet fair-haired boy had his first day at Eton, how he used to come into the office during the holidays, all shy and awkward. Now he is 6ft- 4, and with this woman, who according to an ex-colleague, Freud paints "beaver and all".

Then there are all these girls who have barely even finished their GCSEs, writing best-sellers in their bedrooms. And of course, the Spice Girls. The "affectionately-named" Baby Spice is twenty-one, 5ft-2, and enjoys such celebrity that - you know what - the competition on the front page of my local paper this week is "a once in a lifetime chance to win Baby Spice's plaster cast". Can you believe that? (She injured her wrist in Turkey last month, apparently). It's just gross.

Next year I will even be too old to go on a Club 18-30 holiday. Not that I particularly want to go, you understand, but I can't bear the idea of being too old for anything. There is, of course, a solution. A friend of mine, who shall remain nameless, has been lying about her age for the last few years. I recently met her in a bar, where she had to prime me at the door: "look, everyone here thinks I'm twenty-eight, OK? Please don't say anything".

We later spent hours agonising over our imminent decrepitude, discussing everything from wrinkle cream to contraception, along the lines of "mine are much worse than yours" and "are you sure that's safe?" After going through Phytocream, Primordiale, Persona, the Pill, and a few gallons of Chardonnay, she had a brainwave: "I know, let's get our belly-buttons pierced". This was a desperate attempt to recapture the flat-stomached, come-and-get-it, don't-give-a-shit golden youth we once knew, but unless I go to Marbella for my holidays and hang out with a bunch of eighteen year olds, who the hell is going to see this thing? Then if the idea of it is to ensnare a muscular young toyboy, what happens - as he too would presumably have a belly-button ring - in flagrante delicto if your rings get caught? The thought is too awful. "No" I said, "it would rub against the waistband of my Nicole Farhi suit, you'll have to think of something else".

She, however is going for it - I hope it helps. Meanwhile I'm kicking myself over the hill with intensive sessions in the gym, lashings of Primordiale, cans of caffeine-loaded drinks and definitely not reading "Cosmopolitan's Thirty Things You Should Have Done by Thirty".

Primordiale Serum by Lancome, pounds 37 from Fenwick, 63 New Bond Street. London W1. Anti-ageing Phytocream, 60ml, pounds 9.85 from Verde, 15 Flask Walk, Hampstead, London NW3.

Navel piercing, pounds 25-75, depending on choice of ring, (about ten other parts of the body can also be pierced ...) Metal Morphosis Body Piercing Studio, 10/11 Moor Street, Soho, London WIV