Food & Drink: The girls' bloodless revolution: Joanna Blythman has sympathy for the growing number of teenage vegetarians. But when one joined her family, her patience was taxed

When my prospective au pair phoned to tell me she was a vegetarian, and asked if this would be a problem, I said categorically that it would not. We were, I explained, a household that inclined in that direction anyway. Red meat we ate occasionally, poultry or fish once or twice a week - a vegetarian would not make much difference. Famous last words.

I had always been censoriously unsympathetic to friends who complained about their teenagers (invariably daughters) who had suddenly become vegetarian. 'All they do is spend even longer in the bathroom messing about with stuff from the Body Shop, only emerging to give you lectures on animal welfare,' said one friend.

When she had stopped ranting like an old reactionary, we established that, however wearing, her daughter did have some legitimate concerns about the miserable conditions in which many animals are reared for the table, which we indeed shared. The difficulty came not with the logic of the argument, but with the consequences. In other words, finding things that she would eat.

'The main problem with Kate becoming a vegetarian is that she doesn't really like vegetables,' my friend moaned. Kate, it appeared, was more anti-things than pro-things in principle - the prerogative of all teenagers. But I had to admit that it must make cooking difficult.

My sister confirmed that the young vegetarian was a rapidly growing phenomenon, saying she had been told that they account for 14 per cent of the 15-17 age group. But she insisted it was more like 90 per cent of girls, based on her empirical observations of daughters of friends and colleagues, plus the series of au pairs who had arrived from various European countries in the course of 10 years.

'The only things you can be absolutely sure that they will eat are baked potatoes, digestive biscuits and Haagen-Dazs ice cream. The German ones eat endless bowls of breakfast cereals and muesli at all hours of the day and night,' she informed me. But the worst of all were what she called 'Glaswegian vegetarians' after our home town. They lived on Coke, Mars bars and chips.

So when Rosie, our vegetarian au pair, arrived to live with us for three months, I was absolutely determined that we would rise to the occasion. This was going to be an opportunity, not a limitation. We would all, children included, eat vegetarian food. I could not bear the prospect of cooking two different meals, still less of offering, as an alternative when we ate meat, those ghastly textured vegetable-protein sausages and rissoles promoted by veggie idols such as Linda McCartney. We would, instead, eat only imaginative and stimulating meatless meals - and love it.

It all went brilliantly at the beginning. For the first 10 days, we ate two totally meat-free meals a day - felafels and tahini sauce, pasta in all forms, vegetable crudites with crusty breads of all kinds, chick-pea stews, millet and vegetable galettes, creamy potato pie, gratin dauphinois, herby omelettes, home-made pizza, mountains of green salad, lentil curries, spiced rice, stir-fried noodles . . . no one complained. The children revelled in the permanent revolution of dishes set before them. Rosie, fortunately, was not a vegetarian of the Glaswegian variety, being open-minded and fairly adventurous. What was more, she would eat fish. The only no-go vegetable was spinach, which she detested. Thus I found myself in the ironic position of dispensing little lectures on folic acid and its benefits for women's reproductive health.

So far so good . . . until my energy ran out. The first hassle was less the flow of ideas than the time factor. It all took ages. People got fed up with bread and cheese and fruit, especially in winter. Baked potatoes became boring too, but everything else took time and effort. Searching for inspiration, I asked Rosie what she ate at home. We established that soup in all forms was a winner. But what about the stock? No quick boil-up of the remains of a chicken was permitted. Not even a ham bone or bacon trimming to flavour the lentil. She suggested stock cubes, but here I was the purist. How could those combinations of hydrolysed vegetable protein, salt and flavourings ever fit into any idea of healthy or wholesome eating? I was scandalised. Stock cubes in my book are on a par with Camp coffee.

The stock debate opened up a gulf between me, as a vaguely demi-vegetarian food lover, and the true vegetarian. I had low tolerance for convenience foods such as ready-made pizza bases, cook-chill cauliflower cheese, nut cutlets and others of that ilk. Principled vegetarians, on the other hand, like them because they do not cause the demise of a living thing . . . whether or not they taste good.

Thus the ritual of making proper vegetable stock began, and Rosie became a willing learner. But there were drawbacks: a kitchen perpetually running with condensation and a house that took on that soupy smell you find in wholefood cafes. But the worst thing was the sheer bulk of supplies that had to be lugged back from the shops. No high energy, slim-line steaks or chicken escalopes. In their place, sackloads of potatoes, stacks of carrots, what seemed like hundredweights of garlic and onions, half a bakery a day. I took to buying things like rice in bulk, stocking up in frontiersman spirit with red beans and molasses. And still we were always running out.

I began to see the market through Rosie's eyes. Walking past those stands with rabbits hung by their hind legs, aged cocks with dangling necks, dark red ox tongue and shuddering calves liver obviously upset her. She would avert her eyes and look away, like a sensitive bystander trying to ignore a public execution. Fish, too, was a delicate matter. Fine if it was a nice white fillet; less so if it was a slippery little squid with one baleful eye, a twitching lobster, or a primordial looking oyster. I realised how I had never really understood the squeamishness that grips many vegetarians. Food lovers take pleasure in the tactile sensations of handling and preparing food. Scaling or gutting a fish is merely part of the job, a chance even to examine the provenance of what you are preparing. To vegetarians, such activities are as repugnant as serving up a newborn baby for ritual slaughter.

Towards the end of the second month, it was the children who began to rebel. 'Why don't we ever get lamb chops any more?' became the chorus. 'Give us meat with bones in,' they demanded. So, when Rosie was away in Paris, I shot out and bought meat. We salivated over roast duck. The kids demolished potatoes fried in goose fat. I made a huge beef stew with red wine and olives . . . the sort of gutsy peasant food I had rarely made before, but suddenly craved.

When we finally waved Rosie goodbye on the plane at the end of her stay with us, there was no problem deciding what we might eat that night. But her stay has subtly changed the way we eat now. Bacon, a foodstuff which I always thought I loved, suddenly lost its appeal. Even free-range, antibiotic-free and dry cured . . . it suddenly seemed like the salty piece of unappealing fat that vegetarians abhor. We had all become aware of fat and grease. I cooked some better-than-average sausages, and no one wanted to eat them.

Overall, I reached one global conclusion. Demi-vegetarian leanings do not necessarily escalate into full-blown vegetarianism. I love good meatless food - preferably not cooked by vegetarians - but I would be terribly sad never to eat a really good stew, roast pheasant, Peking duck or tender gigot of lamb again. It took a vegetarian to show me that, for which I am eternally grateful.

(Photograph omitted)