I was fine until I saw the needle the surgeon was proposing to stick into my chest. Five inches long, and blunt. During my consultation earlier, he had referred to it as a 'knitting needle'. I had thought he was joking. More fool me.

But if I wanted an instant bust, this is what was going to do it. I saw the photographer and her assistant looking queasy. Oh dear. I shut my eyes.

Once upon a time, I had breasts. They may have been only an A-cup, but they weren't bad. However after three rounds of breast-feeding (during which they swelled to a magnificent 38EE) they dwindled and for the past few years, I've had to use gel pads to fill out an AA cup. I don't need to wear a bra at all, except that I can't bear looking utterly flat-chested. Erin O'Connor can get away with it - I can't. I've thought about surgery, but it's serious, expensive stuff and needs lots of down-time. And what if something went wrong? But then, just recently, along came Macrolane, an injectable filler swiftly dubbed, to the despair of its makers, the 'instant boob job'. A half-hour, nonsurgical procedure that can give you an enhancement of up to a cup size that is supposed to last for a year.

'But it's brand new,' said one colleague, aghast. 'How often do you tell your readers not to be guinea-pigs?'

I could see her point - any procedure carries a risk, however small, and this is something that has yet to become mainstream. It would be safer to just try a better bra manufacturer. However I discover that Macrolane is from Q-Med, the company that makes the wrinkle-filler Restylane. It's the same stuff - a stabilised form of hyaluronic acid - but in bigger particles. I wouldn't go near many fillers on the market, but, I reason, the Restylane family is considered to be as safe as they come.

Because results for any injectable treatments depend on the practitioner's technique, I also take the precaution of booking in with Chris Inglefield, who is leading the clinical research into Macrolane and so the top man for it in this country.

It's a mistake to think procedures of this sort as 'lunchtime fixes'. I'm not able to just walk in and have it done. The surgeon assesses my suitability for treatment (Macrolane can be used for reshaping breasts and correcting asymmetry; it can also be used for shaping buttocks or filling out dents from bad liposuction). I must have a mammogram. I take pre-emptive painkillers and antibiotics. By this point I was feeling less calm about the whole thing.

It helps that Inglefield has a kindly, reassuring manner, even if he was squaring up to me with a needle, dotting felt pen marks around my exposed top half. He set to work injecting first large quantities of anaesthetic (uncomfortable, but not agony) and then the filler. It was all over in 10 minutes.

'Yes, you've got boobs,' he observed, seeing my astonishment when I opened my eyes and gawped at my new bust.

He may only have added 10cm each side but to me the difference is staggering. I could have kissed him. In fact I think I did. The rest of the day is a bit of a blur since I felt drunk on the anaesthetic. I was restrained from wobbling home on my bicycle, and put in a taxi instead, with my new assets safely strapped up in a sports bra which I was told I had to wear day and night for a week - the gel wouldn't move from where it had been put, but it was as well 'to keep everything quiet'.

My husband was only allowed a cursory, hands-off viewing, but he was impressed. The pain kicked in later when all the anaesthetic and adrenaline wore off, halfway between premenstrual tenderness and the engorgement of breast-feeding.

The next morning, everything hurt even more. Taking a deep breath was a challenge. But did I care? Not a jot. Perhaps that's the effect of having bigger breasts. They're still not quite a B-cup but to me they're astonishing. Happy every after? Let's hope so. At least, until I need a top-up and must face that needle again.

· Chris Inglefield, London Bridge Plastic Surgery 0845 009 2775. Macrolane injections cost around £3,000. macrolaneuk.com.