Needless to say, the boys called him "Junket" and his last end- of-term ball was billed as "the final junket". But now that John Keyte is stepping down as headmaster of Beaudesert Park, the preparatory school at Minchinhampton, near Stroud, thousands of former pupils and parents acknowledge with more than a twinge of regret that a unique era has come to an end.

Throughout its 87 years, the school has been in the hands of the same family. It was founded in 1908 by Arthur Harry Richardson, who ran it with his wife, Marjorie, until 1938. Next, their sons Austin and Barton and their son-in-law Vincent Keyte presided as a triumvirate. Then in 1970, Vincent's son John took over.

Beaudesert began life in a house of that name in Warwickshire, near Henley- in-Arden, but after only 10 years the need for more space drove the founders to the present spectacular site, high on the lip of a Cotswold valley near Stroud. The name came with the school, and to this day it ties Gloucestershire tongues in knots, emerging as "Boadicea" and "Bewdizy", among other bucolic variants.

The new home was a splendid, if improbable, house built during the 1870s for the Bishop of Gloucester: a mock-Gothic, half-timbered, black-and- white palace, which stands out aggressively from its sober limestone neighbours. Fortunately, the pioneers also planted many trees, so the school grounds are now graced by magnificent Wellingtonias and beeches.

The one drawback of the property was that it included no flat ground for playing fields - and still the school's sports fields lie half a mile away across Minchinhampton Common. There is some compensation in the fact that, for minimal fees, pupils can use the golf course on the common, sharing the fairways and greens with itinerant cattle. Were I a boy again, Beaudesert's rural surroundings would be one of its main attractions: tree-climbing (highly educational) is allowed, with parents' permission, as is the building of huts or dens; and I am glad to see that country matters have often loomed large in the curriculum. When food was short during the First World War, the headmaster took senior boys on armed forays after rooks, which were then cooked in pies and served up for lunch.

A generation later, the school responded to rationing by starting a pig club, with sties at the bottom of the kitchen garden. Half of every animal slaughtered had to be sold to the community, but boys and staff ate the rest.

A montage of sketches and notes from the Thirties reveals that in those days navy-blue serge suits were de rigueur, as were cross-laced boots and bowler hats. Today things are more relaxed, but an element of formal discipline still prevails: pupils address masters as "Sir", and leap to their feet when the head comes into the room.

Although Mr Keyte modestly ascribes the school's good health to luck and its central location, there is no doubt that in recent years the place has been run with imagination and efficiency. In 1968 it became an educational trust, which enabled it to launch appeals, and in the past five years more than pounds 1m has been spent on new buildings, principally the indoor swimming-pool and the pre-prep block, each of which cost about pounds 400,000.

While other private schools in the neighbourhood have closed or amalgamated, creating a dearth of opponents at cricket and football, Beau- desert has flourished. It now has 270 pupils (girls as well as boys), with an average class size of only 16, and its facilities are enviable.

The computer system, for instance, has 50 terminals. On the day I visited, 11-year-olds were making up television advertisements for holidays of their choice: one boy, having heard Beethoven's Pastoral Symphony at home in the evening, was grafting the first movement on to his videotape. Another class was working at a classical version of Trivial Pursuit. Having thrown the dice, a boy was required to parse ii.

"It's the first-person perfect of eo."

"And what does that mean?" asked the master.

"I go."

This weekend John Keyte goes, after 33 years, or 100 terms, teaching maths to say nothing of his own five years at Beaudesert as a pupil. His successor, John Beasley, comes from Eton - a perfectly good school, but not well endowed with facilities for tree-climbing.

One of the new head's more ticklish problems will be to resolve an anachronism which blights the Beaudesert song, written in Latin during the Twenties. Two lines exhort every boy (puer) to strive hard at work and games. Someone, somehow, will have to magic away that awkward masculine noun so that the sentiment can embrace both sexes.