"I woke up at 5am and thought I was going to throw up. And I've been s-h-i-t-t-i-n-g myself all morning," confides one mother. "I told him it doesn't matter as long as he does his best. But of course it does. I'll kill him if he doesn't do well," says another.
They are suffering from a vicarious bout of pre-exam nerves. Any minute now their offspring, aged between six and 11, each wearing a colour-coded badge, will be shepherded into groups and disappear through the school doors. Here they will sit a formal examination, most of them for the first time. It is only a mock examination, but for their parents the results are of vital importance. They will indicate whether their children, the majority from state primary schools, have a chance of passing the entrance exams next year for a highly sought-after place in one of London's independent schools.
That such a mock exam exists at all indicates the anxiety about state secondary education gripping the city's middle-class parents. Most of the parents here this morning would never have considered private education a generation ago. As the first paper, English, gets underway, they lurk in the playground before driving off in a collection of functional estate cars. Many speak enthusiastically about their children's primary school and would prefer to continue their education in the state sector, not only because it would save them thousands of pounds a year, but because of the broader social mix state schools offer.
Oonagh Blackall's daughter, Alice, who is sitting the mock as preparation for four entrance exams in 1996, goes to a much in demand primary school in Putney, where many of the top class go on to independent schools. Mrs Blackall speaks for many: "I think a lot of these parents don't have an option. If there was an extension of Alice's primary school, I think many people would be happy with it. But what the state offers in this area is very poor. People are pushed into the private sector who don't really want to go that way." A higher proportion of parents in London send their children to independent schools than in the rest of the country (10.3 per cent compared to 7.2 per cent) and that proportion has risen significantly over the past decade.
Parents like Oonagh Blackall complain that there is no longer a middle ground in the capital between highly academic, elite and usually single sex private schools and comprehensives where co-education and social integration are offset by weak academic results. The Government's league tables of exam results, which show these extremes in stark relief, only make parents more nervous. The smattering of selective state schools that do offer some kind of middle ground - the Oratory, for example, where Tony Blair is sending his son, or Lady Margaret's in Fulham - are far more difficult to get into than their independent counterparts. Not that they wouldn't do nicely, thank you. "I hope to God he gets into Tiffin [one of the most oversubscribed London state schools],'' says one mother, a state secondary school teacher, to her friend. "I don't even earn enough to cover the Latymer fees. It would be nearly pounds 18,000 a year for our three boys. How will you manage?"
Disillusion about state education sets in because parents feel their child is not doing as well as he might, or because of stories they hear about their friends' teenage children at comprehensives. Once sparked, the anxiety catches like wildfire. It takes a cool head not to be swayed by the endless neurotic discussions at the school gates, and to recognise that the good and bad reputations of different schools are founded as much on rumour and hearsay as real knowledge.
Even parents who are entirely happy with their state primary balk at the prospect of sprawling comprehensives with gangs of big teenagers. They may approve of the vast social mix but, if they're honest, they admit it also makes them nervous.
"Some of our local comprehensive's results are quite good. But there is also an element in the school which is not so good," says Virginia Nelson, who entered her young son Matthew for the mock exam last November as well as this year, to give him advance warning of what would be expected in entrance exams for King's College Wimbledon, Latymer and Hampton. She remembers how nerve-wracking it was when her older son did the rounds of the exams last year, and some of his classmates were rejected by all their independent choices and had no state standby.
"My son is very easily impressed with the children around him and if they thought the thing to do was glue-sniff, or whatever, I think he would probably try it," she says. "I felt that by choosing a private school I wouldn't have that worry so much. It's not that it's not there, but I think the staff are watching for these things much more, they've got smaller classes and more facilities."
Fear of drugs makes parents desperate to find schools which will nurture a range of distracting interests through clubs, music and after-school activities plus a peer group who won't laugh at people who play the violin.
But ultimately the great attraction of private schools is that parents feel they're on familiar territory. The emphasis on good spelling, neat handwriting and times tables is probably very similar to the way they were taught themselves - even if they went to state schools. And it can be a huge relief to see results in black and white. Oonagh Blackall says: "In state schools you know if your child is doing terribly badly or terribly well, but if they're somewhere in the middle you've got no idea what you should be aiming at. That is hard as a parent because it's difficult to be objective."
But the decision to switch to the private sector hardly signals the end of all their worries. Even a clever child may not get in because there just aren't enough places to go round - about one for every four applications on average. Independent schools which take in a high proportion from state schools (in some cases as many as 60 per cent) have the biggest entry at 11 rather than at 13, when the traditional route is via Common Entrance, still preferred by the most academic schools such as Westminster and St Paul's. Children who succeed at this hurdle will probably have been in the private sector for years. Meanwhile, prep schools attached to the top boys' independents have lowered the age of entry to seven and eight to catch the brightest children as early as possible, which means some take the entrance exams as young as six. The effect of all this is to make the schools that seem unattainable all the more desirable.
Hence today's mock exam. It has been organised every year for the past four years by Holly Sandys and Jennifer Preston, both educational consultants. They divide the rest of the year between assessing and teaching children who are having problems at school, as well as tutoring for what Mrs Preston calls "this awful business of passing exams". After 20-odd years they recognised that the entrance exams could trip up even the brightest and best when they are competing against highly exam-literate prep school pupils. "Children changing from state to private really need a year's tutoring to make sure they've covered everything they need to know. Very often they need to move further on with maths and get more experience of writing detailed answers to comprehension passages," says Holly Sandys. Spelling, punctuation and presentation are also likely to need tightening up.
Mrs Preston tells parents that children need to be at least two years ahead of the national average to get into a good independent school, enough to make the hearts of many primary school parents sink.
The lengths they will go to to help their children catch up are extraordinary. They must put their names on a long waiting list for a good tutor (Jennifer Preston is booked up until 1998, and already has bookings for the year 2000) and shell out considerable sums of money - pounds 120 for an academic assessment, about pounds 20 a week for tutoring for at least a year, pounds 45 for the mock exam.
All this time and money doesn't guarantee peace of mind, however, as Julian found when his son sat the mock: "I looked at some old papers and I couldn't answer some of the questions myself. So what chance has this boy got, who has been swimming in his class of 35 at the local primary, where 80 per cent of the time he's been making things out of papier-mache?"
Julian, a self-employed architect who was himself educated at the local grammar, had been an enthusiastic supporter of his son's primary until a crisis of confidence set in when his sons were ten and eight. "The teacher would say 'He's doing so well' and we'd say 'Yes but he can't spell...' Part of the problem is that we are now telling them to forget all the things we've said in the past, like it doesn't matter if you don't win, it's the taking part that counts. Suddenly we're saying go into this exam and be brilliant, it's really important, you must pass. It's our first taste of a system that doesn't recognise anything that has gone before.
"At the moment I'm going through this terrible panic that I've fucked up from the word go. I went to look round one very academic school in south London last year and another father said to me, 'As long as you've got your lad in the right streamer school from the beginning he's bound to make it into this place.' His boy had been at some junior St Cake's from the age of four. It made me feel absolute despair and self-hatred."
Back in the playground the final break between papers is nearly over and the bigger boys are getting a bit wild. Jennifer Preston's daughter, Eleanor, who helps every year, looks on wryly: "You can tell how difficult the papers are by the level of hysteria in the breaks. The more nervous energy they've got, the harder it's been." The girls chat seriously in small groups. many of them know each other from school or because they go to the same tutor. In Alice Blackall's primary school class most of the children are being tutored. Alice's mother Oonagh says, "The children all talk about their tutors - I think they feel slightly left out if they haven't got one. It's awful, it's like an accessory."
At 11.45 the children go back to their classrooms to sit the final paper. The whole morning follows the same pattern as the schools' entrance exam mornings, with papers in English, Maths and Reasoning, each lasting between 45 and 75 minutes and comparable in style and content to the real thing. There are drinks and biscuits in between. Those trying for the most academic schools do an extra maths paper or sit an exam designed for children a year older.
Meanwhile the six- and seven-year-olds work through a series of short tasks on their own, with three invigilators on hand to help or explain if they get stuck. The atmosphere is formal but friendlier than the real thing.
Although independent schools are often highly secretive about the contents of their entrance exams, Jennifer Preston and Holly Sandys make it their business to find out what's on them. And so far the mock has proved to be an accurate indicator of results in the entrance exams. Holly Sandys says, "The children who got scholarships were the ones who came top in the mock, and so on. Immediately after the first exam we were getting requests for the next one, so there was no question of not doing it again. It was taken out of our hands."
Every year, about an hour before the end of the mock, anxious parents trickle into the playground to wait for their children: it's an unmistakable sign of nerves. There's a huge relief when they see that their child has come through the ordeal. But the post mortems follow the big hugs with indecent haste: "How did you get on? Did you finish? What was the maths like? How long was your story?" They soon discover it's a big mistake. "It was horrid mum, it was really hard. There were 16 pages of maths but I only did 13. And I couldn't finish the comprehension either."
"Never mind darling," comes the brave reply, "it was only a practice, have a crisp." And they wander off into the New King's Road to face their uncertain future