Women’s magazines are always telling us to refresh our make-up, or to wear a new shade of eye shadow, or not to get stuck in a make-up rut. (I’m delighted liquid eyeliner and red lipstick are back, but since I’ve been wearing both since I was 15, it’s hardly an exciting departure.) The truth about make-up, even if you love it as passionately as I do, is that you can have shelves full of the stuff, and more sable brushes than you know what to do with, but success or failure is all to do with the application. You really need to know what you’re doing, and few of us actually do. I, for instance, can do one look (red lips, flicky eyeliner) perfectly, and that’s it, yet supposedly that makes me “good” at make-up.

When I’ve had make-up applied professionally, I’ve always been surprised that the make-up artist uses exactly the same products that I do, but with a completely different result, even with something as foolproof as foundation. You’d think that once you’ve got the shade right, it can’t be that hard.

And, even though I’m 41, I still don’t know how to put grown-up eye shadow on properly. If I try to do that graduated shading thing, I look like Sheena Easton circa 1982, or end up with dirty-looking smears. I want to know because, short of surgery, there is nothing that can completely alter your face as comprehensively as really good make-up. Time, then, to call in the expert.

And Mary Greenwell really is the expert. I’d use the words “ grande dame”, except she’s not old enough. She started early. She was there in Paris in the 1980s, the week the supermodels were born. They all stayed in the same little hotel, and Mary sat about doing their make-up, and Sam McKnight played with their hair, and Stéphane Marais, Laura Mercier and François Nars were milling about – and suddenly, boom, a phenomenon occurred overnight. And Mary was at its epicentre. She has, needless to say, endless magazine covers to her name (Diana, Kate Winslet and Gwyneth Paltrow have been given her magic touch). She’s worked with every big-name photographer from Annie Leibovitz and Helmut Newton to Mario Testino, and has trained anyone who’s anyone as a make-up artist.

Now she has started a sideline as an occasional make-up teacher. “Fashion is for the very young, and for them it’s incredibly exciting. But make-up has got very ‘edgy’ and I’m not into that. I’m into beauty and enhancement.” Under the auspices of the Premier Hair and Make-up Agency, Mary is running a series of London workshops. “I’d never tell anyone to change their make-up completely, just to update it,” she says. “It’s about a small series of tweaks that make the most amazing difference, like suddenly nipping in a jacket, changing a couple of buttons, and – wow. Women mind about looking mumsy when they don’t feel it, and I can fix that. Not that many women are aware of the changes in make-up in recent years – but there are some really extraordinary products out there now, ones that do incredible things.”

But, of course, you stand in the beauty hall, bewildered and short of time, and end up buying your usual lipstick from your usual counter. “Exactly. Everyone’s done a Touche Eclat, for instance, but how are ‘ordinary’ women supposed to know which is the best one for them?”

Mary knows, and, if you attend her course, will even take you shopping for it. Mary knows everything. She knows, for instance, that if she shortens my brows by 1.5mm, my whole eye area will suddenly open up dramatically. She knows which four products will take minutes to apply but make me look miraculously fresh and pulled-together first thing in the morning. She knows how to do a “nude” face on me. Whenever I’ve tried this in the past, it’s looked like I’ve been dunked in beige paint, yet here I am, looking pretty damn fine and paying my own little tribute to J.Lo.

Mary knows how to give me enormous feline eyes (which garner an embarrassment of compliments later that night, including “Have you had work done?”) and a killer pout, the latter achieved by using shades I wouldn’t normally go near but have now stockpiled. And she shares the knowledge, explaining at every step, so that now I know too.

She is a sort of magician, reinventing your face with every dab of her fingers. Mine goes through several incarnations, from “natural” – it looks like (artificially) great skin and mascara, but involves rather more than that – to seriously vampy. At no point do I look like I’m wearing a truckload of make-up, even when I am. I’m tired and stressed, but Mary makes me look great at every turn – and (big plus) she’s heaven to chat to, and very funny. Most of all, though, this hasn’t simply been a fun day out, or a one-off makeover. I leave the studio full of information, tips, techniques and advice, and go home and chuck out half my make-up. I haven’t looked back (or better), and eye shadow is my friend. I feel like I’ve had a writing lesson from Saul Bellow, or been taught to sing by Maria Callas. As the ad says: priceless.

MARY’S MAGIC POTIONS

— Chanel Teint Innocence in compact form: it gives a flawless airbrushed look
— Issima Precious Light – Smoothing Illuminator by Guerlain: it truly seems to lift the areas that need lifting
— Prestige Liquid Eyeliner: it gives the darkest line of any I know
— Diorshow Mascara: iconic in its lengthening and thickening
— Chantecaille Cheek Shade in Winter Bloom: because it gives the best natural warm glow

A one-day make-up workshop costs £1,000; a 10-day make-up artist course is £5,500; www.premier-workshop.com

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