My daughter has been crying — nothing unusual about that I suppose. She is 15, and girls do cry — when they’ve argued with a friend, not been invited to a party, or failed to get the mark they wanted in exams. But actually, it’s none of those things. The reason is that the school Charlotte has been a day girl at for the last four years is closing. “Why, I don’t understand . . . we love it here, why should we have to leave?” was all she and her friends could say.

The school in question is Bedgebury. It’s an 80-year-old £4,500 a term girls’ school, famous partly for its “celebrity” alumni such as Trinny Woodall. Set in 200 acres of Kentish parkland and forests, with ponies stabled in the grounds, the school was a grade II-listed French-style chateau — a dreamland for children. It was, as one child told me, “too perfect to last”.

But why? After all, Bedgebury had huge plusses. The school was only 50 miles from central London, it provided a good education (91% of all GCSE students gained the magic A-C grades last year), and managed to teach both academically able children alongside those with dyslexia and other learning difficulties. How could it fail? The news arrived in a letter at Easter, informing us that the school was to merge with another, thus sustaining “the name of Bedgebury into the future”, said the head. A shock in itself. But, as it turned out, contracts hadn’t been signed, and the other school pulled out. So Bedgebury had to close.

Bankruptcy was not the issue here, a parent action group was told. Projected numbers were down — apparently only by 15 or so — but that was enough to tip the balance into deficit. The “demographics” were said not to look good. The national birth-rate is static, and private schools are reportedly bracing themselves for falling numbers. All-girl education is under threat, too. There is a general push towards co-education, certainly from 16 onwards.

For the 200 or so Bedgebury girls aged 11-18, this is a personal tragedy. Not on the scale of losing a parent or sibling, or parental divorce, but not far off it.

Girls who have taken years to build up relationships with their peers are going to have to start all over again at another school. Some schools have quickly cherry-picked the best Bedgebury candidates, not wishing to dilute their exam results with less able pupils. So where once there was a sense of inclusion among the girls, there is now division.

The other problem is the minefield that is the modern exam board system. There’s now such a proliferation of exam boards that no two schools are alike in what they teach. This is a particular problem in year 10 (my daughter’s year), who are midway through a nine-subject GCSE course. So to add to my daughter’s (and my) stress levels, we have had to do the rounds of local schools, sitting exams and tests, trying to find somewhere that can shoehorn her GCSE choices into their exam system.

We’ve finally opted for a good local girls’ school which will take Charlotte and four of her friends.

What then, can be learnt from this catastrophe? For the 500,000 families who do choose private education, it is a warning bell. No school, it seems, is safe from market forces. As parents we examine a school’s record, its exam results, its after-school clubs. But how can you check a school’s financial accounts or its projected pupil numbers? Or even know there’s a problem at all, if the school chooses to keep quiet about it? Compared to others in the same situation, though, we’ve been lucky. We were given a whole six weeks’ notice of closure, whereas parents at Parsons Mead, a school in Surrey, got only four — about the same as parents at Newlands school in East Sussex. So far this year, several private schools have announced precipitate closure plans — and more are forecast.

Many Bedgebury parents have mortgaged houses or spent savings to give their daughters, some crippled by dyslexia or dyspraxia, the chance of a good education. There are feelings of impotence, betrayal and sorrow. One mother told me, “I feel as if I’ve been divorced and I didn’t see it coming.” Another sobbed, “I feel a kind of grief, it’s as if we’ve lost our home.”

There’s a postscript to this story. Last weekend we received a valedictory letter from the headmistress, Hilary Moriarty. She reminded us that Bedgebury had its best-ever A-level results last year, rising “140 places in the Sunday Times league table”, adding, “I was so proud of the girls and staff that I thought I would burst.” Well, all of us Bedgebury victims — parents, children and staff — are bursting too, but not with pride.