YOUR daugher is 10; you have loads of money to spend on her education. You have read all those league tables of A-level results, and would secretly like to send her to one of the top 10 schools. But will she get in, and if not, will she be scarred for life? Don't those tables of examination results actually give about as many clues to what schools are really like as car number plates do to drivers? And should you just be looking for an efficient exam processing plant? After all, look how far the Princess of Wales has come, just having good manners and being kind to old people.

The options open to monied parents of girls are greater than ever before. A smart London day school makes the soundest financial sense, practically guaranteeing good results for around pounds 5,000 a year or less - half the cost of boarding. But day schools have a reputation as academic hothouses; parents understandably wonder how pleasant that really is.

Long gone are the days when girls' boarding schools taught deportment, lacrosse, and little else: competition from boys' public schools (only 69 of the 233 boys' schools belonging to the Headmasters Conference now don't take girls) has put a stop to girls' school boasts about how cheap they are, encouraged them to invest in technology labs and marketing consultants, and propelled them up the academic tables, so important for guaranteeing next year's bright intake.

There are still a few girls' schools which have failed to find the means or will to change; still dwelling in the marshy hinterlands of academe, where 'facilities' means an overworked toaster in a drab common room, and girls spend five years feeling cold and watching Neighbours - but they are fewer and farther between every year.

The furore over the sacking of the High Mistress of St Paul's Girls' School (feees pounds 5,652 a year, and fifth in the league tables, making it the most successful girls' school in the country) demonstrates the impact this competition has had. St Paul's has almost nothing to fear from Marlborough or Charterhouse (ranked 85 and 53 respectively), but press reports of maddened parents and hissing girls, apparently determined to oust Helen Williams for her rather avant-garde view that 11 GCSEs are not necessary, show just how much power parents now wield. Their clever daughters would have been welcomed with open arms by any other school with an eye on the exam tables. And with so many schools in the marketplace, governors have to take parents' views of what constitutes value-for-money seriously.

The St Paul's mythology has it that pupils are all catwalk queens with brains - 'but most of what you hear is rubbish,' says one parent with two daughters at the school. 'You get about 500 applicants for about 100 places, so you get an awful lot of pissed-off, influential parents, whose daughters didn't get in, spreading bad things at South Kensington drinks parties. Unlike many top girls' schools, there's no back door at St Paul's. It is not an old money school, but very meritocratic.'

Pupils dismiss the idea that they are all super rich. One girl who has just left said: 'I can only think of two girls in the Ferrari-for-the-17th-birthday bracket.' And they don't agree with the notion, put about in the papers, that the High Mistress was deposed because she lacked glamour.

Glencora Senior, 17, who with 13 others in her year got 10 straight As in her GCSEs, says: 'The press have completely distorted things, for example they said it was apt that Paulina rhymed with eyeliner and they went on about what Mrs Williams looked like. It's completely untrue about parental and pupil pressure to oust Mrs Williams - it was a matter between the Mercers Company and the staff. Some parents probably preferred Mrs Brigstocke (Helen Williams' predecessor) because she was always in the papers and they liked inviting her for dinner, whereas Mrs Williams wasn't interested in dinner parties and free tickets.'

The fact that the model and actress Catherine Oxenberg was at St Paul's has left some people with the idea that the average Paulina snatches a break from the photo session at Vogue to revise calculus. And sure enough, Thomasina Miers, 16, is just this sort of having-it-all Paulina.

'I love catwalks. It's difficult at St Paul's to have much of an ego, because there's always someone more brilliant than you, but it's a different sort of competition on the catwalk and you get a terrific ego boost. I've got 10 As in my GCSEs, and I'm hoping to take four A-levels. Everyone at school is appalled because next year I'm going to be a deb, but my parents want me to, and I want to for parties, and fun.'

Ninety-five per cent of Paulinas go to university; 40 per cent to Oxford and Cambridge; but these impressive results should be considered in the light of how difficult it is to get in in the first place. Last year, 339 girls sat the exam for 78 places, and on the whole, only the brainiest apply.

Things are hardly easier at the other top London day schools, despite their marginally less fast-set image: schools like North London Collegiate, South Hampstead High School, City of London School for Girls, Godolphin and Latymer and James Allen's Girls can all be very picky about whom they accept.

Many schools have to effect alchemy with much baser metal; there are still some independents where the attainment of five GCSEs ranks you as a prodigy. Sophia Neal, 30, recalls Southover in Sussex (now closed): 'They took anyone who couldn't get in anywhere else. Looking pretty and finding a rich man to marry were the main aims. We used to assess each other in terms of 'big eyes', 'nice hair', 'good figure' and so on. Most girls left to go to live in London and cook. It really didn't matter if you were innumerate, so long as you knew the name of the Master of Foxhounds. It was desperately snobby, but if you weren't in Debrett's, a lot of money helped.'

Recession, plus competition from the new coeds, means girls' schools which don't produce brilliant results now have to offer something else quite special. Sue Hopkinson, headmistress of Stonar School in Wiltshire (pounds 8,100 a year), admits hers is 'not one of the enormously successful elite schools, although we take academic life seriously. But we have an equestrian centre, and girls can bring their own horses and train as riding instructors.'

These days, no self-respecting school can afford to ignore results, but some can still offer People Like Us. An old girl from St Mary's, Calne, (notorious for expelling Jade Jagger), comments: 'For seven years you were with exactly the same type of girl from exactly the same type of background as you. We were the children of fourth or fifth generation public school parents, who placed great importance on status. An important but unspoken part of things was that your father was something in the City, and you had a house in the country and a flat in Chelsea. If he wasn't and you didn't, it wasn't quite right. I felt I wasn't in the real world.'

But at the best boarding schools, while girls may well be able to write charming thank-you letters by return of post, this is no longer the main aim of education. Cheltenham Ladies' College, which used to offer deportment classes where the mistress in charge shouted 'Alack] alack] what a deplorable back]', now offers Japanese, and came 12th in the tables. At Benenden, the Princess Royal's old school, there is a multi-million pound technical centre; Gillian duCharme, the head, says: 'About seven years ago, when I came over from the States, I was surprised by how very different parents' aspirations were for their sons and daughters. They were going to spend their money on the boys because the girls would get married. Now there is a much greater sense of equality, as parents recognise that a first-rate education, excellent facilities and a wide range of courses are equally important for girls.' Benenden girls, under Mrs duCharme, are purposeful and cheerful, in a way that budding poets and philosophers say can be a bit wearing.

Sarah Mulvey, who was in the sixth form last year, identifies a definite Benenden type: the sensible girl, always on the lacrosse pitch, who will go out and do her best. 'Happiness is very important here - or at least, the appearance of happiness.'

Wycombe Abbey girls meanwhile have a reputation for keeping up their hockey while they run a section of a merchant bank, and always being able to wire a plug and change a tyre. Old girl Lucinda Matthews, now 29, recalls: 'We used to sing the school song a lot and then shout - 'Up School] Up School]' The whole ethos was that it was important to beat everyone at lacrosse and at life. You had a sense that you were the creme de la creme, but standards were punishing. Even though I was doing four science A-levels I was expected to discuss Ulysses with the headmistress and speak Italian.'

For a mere pounds 24,000, it is possible to put a daughter through the sixth form of a great boys' public school. But recent expulsions for sex on the premises at some, and allegations that a 15-year-old girl was put on the pill while at Marlborough, have worried prospective parents. Alison Willcocks, deputy head of Bedales, fully-mixed for nearly a century, acknowledges that 'sex is a minefield. It's absolutely unrealistic to suggest boys and girls won't form attachments. Some schools have attempted to outlaw public displays of affection. We are more pragmatic, but we make it plain that sex at school is liable to lead to removal.'

'I wanted my daughter to go to a mixed school so she wasn't silly about men and didn't go round falling in love all the time like I did when I was young,' says a Marlborough parent. But in the event her daughter was not happy: 'If you got under the skin of a powerful boy and you didn't want a relationship, you could have quite a tough time.'

'They should set up a support system so that girls feel able to say 'no' to sex if they want to, without the pressure of a 'prig' tag,' says another Marlburian girl; 'and boys must be re-educated that sex is not an automatic perk of coeducation'. A girl from another school similarly describes how the boys devised sounds to express their opinions about a girl's looks: 'If a girl was considered plain they used to make the sound of a car crashing whenever she came into the classroom.' She became bulimic, frustrated at not being able to be herself but having to be 'an ornament to make the boys feel good'.

That said, if girls can have a hard time at these schools, so can boys. 'If it's stressful being a banana thrown into a cage of monkeys,' says a boy from Uppingham, 'it's not much fun being a caged monkey when there aren't enough bananas to go round.'

Recession, Lloyds losses, and most of all, the decision of boys' schools in the mid-Seventies to start taking girls, have all forced a bit of healthy competition into the previously cheap-and-cheerful, hearty-yet-refined world of girls' schools. Standards are higher than ever before, facilities better, and there is more emphasis on educating girls to run the economy as well as the household. Rich people, faced with such a troubling range of choices, may wonder whether they wouldn't be better off poor with no option but to send little Sophie to the comprehensive.

(Photographs omitted)