Education: How many prefabs fit in one garden?: Wendy Berliner visits a school bursting at the seams

The financial nerve centre of The Cedars Upper School in Leighton Buzzard, Bedfordshire, a school with a pounds 3m annual budget, is a converted storeroom not big enough to swing a cat. An office to one full-time and one part-time secretary, it is also the school shop.

Such is the pressure on space in this highly popular suburban school, the headteacher, Michael Gaches, moves out of his office to work on a table in the corridor to make room for A-level language orals. GCSE orals take place in a nearby church hall.

The Cedars is a school with 955 permanent places and more than 1,293 students. This September there will be more than 1,375 students and in September 1995 probably 1,410.

To fit them all in it has 20 mobile classrooms, three of them shoe-horned in only a few days ago. One, planted on a small garden where two cherry trees were in blossom this spring, is barely a metre from part of the main building. Sheer numbers qualify the school for another two mobile classrooms. Sheer lack of space means that no more will fit.

Yet when popular schools are allowed to expand, this school will be under pressure to take even more pupils. This year there were 345 requests for the 311 places. Fifteen families appealed, three successfully. Last year there were 11 successful appeals and tutor groups were too big as a result.

Mr Gaches, head for the past seven years, is against expanding the site. He feels it might damage the very parts of the school that make it so attractive to parents. He would prefer, instead, for schools to have maximum and minimum numbers for pupils.

'I think a school has some kind of golden mean in terms of numbers. When that number is exceeded I think there comes a point where there is a decline in the quality that is on offer,' he argues.

For him 1,300 is the optimum size for a secondary school. 'Bigger than that and it ceases to be an institution that is one school. It has to be divided up. But one of the great strengths of a school is the student and parent association with that school - a feeling of belonging and purpose, a community feeling.'

It is not hard to see why The Cedars is so popular. Even the mobile classrooms cannot spoil the attractiveness of the pleasantly landscaped site, the low-rise 20-year-old brick buildings abutting rich farmland.

The place is immaculate inside and out. It has the best public examination results for a comprehensive in Bedfordshire - 61 per cent of pupils got at least five grade A to C GCSEs last year - and this autumn there will be nearly 400 in the sixth form.

Discipline is good, uniform is worn and classrooms and specialist rooms buzz with purposeful and orderly activity. The school serves a predominantly middle-class community and has strong parental support. It was always meant to have 1,200 permanent places but this was temporarily pruned because of spending cuts in the early Seventies, when it was built. The county council is now pushing ahead with plans to add the extra places to the site with building beginning in 1996.

Meanwhile, the school carries on with mobile classrooms that are too hot in the summer, too cold in the winter and too far from the resources centres in the school.

Mr Gaches asks what effect all this making do and mending is having on the education the children get. How much worse might it get with the barriers to size dropped?

'If you have second-rate accommodation, you have a factor that militates against achieving the highest quality of standards,' he says. 'I think our standards are already affected and I am not happy about it. We are achieving at a high level but how much higher could it be if we had the best accommodation?'