I was already knee-deep in muddy water when I stumbled against the monk. I felt my body being dragged further into the mire; a second later I emerged, cold and wet to the waist, my arm around the monk as I hauled myself free.

I should explain that a monk is a wooden, stepped device used for measuring water depth, and I was on a National Trust working conservation holiday at Stowe Landscape Gardens, near Buckingham. The activity for Thursday was 'clay puddling', which involved treading lumps of clay into a leaky lake in order to raise the water level. All morning we had been jumping up and down on the clay, splattering each other with mud as we enjoyed renewed permission to be children.

The Trust runs more than 400 weekend and week-long volunteer projects each year. Volunteers pay around pounds 35 for a week in a Trust base camp, helping out with tasks ranging from dry-stone walling and fencing to footpath construction and woodland management. No special skills are needed; the holidays are open to anyone who is reasonably fit, including people with disabilities. Anyone completing a week receives a 'volunteer card', which effectively gives them membership of the Trust for a year.

This trip had a particular significance for me: the mansion at Stowe is now a public school, and I was a pupil there in the Seventies. I had hardly been back since, and the tingling started even before I reached the gates, as I followed the straight three-mile drive from Buckingham. Classrooms and cricket fields stirred long-repressed memories, and when Colin, our volunteer leader, told us we would be staying in the sanatorium, my mind went back to the two days I spent there suffering from a boil at the age of 13.

The sanatorium has not changed (it is as grim as it sounds); but in most respects Stowe is the luxury option for Trust volunteers. On other projects, they are expected to produce their own meals, on a rota basis; at Stowe, the kitchens were turning out food for the summer conference season and we simply joined in. Instead of cooking and washing up, we spent evenings in the school's swimming-pool, on the tennis courts or golf course, or, one night, in a fruitless badger-watch.

Daytimes were different. Work started at 9am and went on until 5pm, with an hour for lunch and generous tea and coffee breaks - plus, as the week progressed, more and more time for 'putting away the tools'. Few of us were used to physical labour - that was why we chose it for a holiday - and the work was exhausting. We spent the first two days digging out two dry 19th-century ponds looking for a spring and an elusive iron grille - 'the search for the holy grille'.

After digging and shovelling and lifting, the most back-breaking task was carting barrow after barrow of soil from the site to a mound 50 yards away. 'What will happen to all this soil?' I asked one of the gardeners. 'We'll get the next lot of volunteers to put it back,' he said. We were not sure he was joking.

After a half-day off, which most of us spent in Oxford, we turned to clay puddling, fencing and lighting fires. The final two days were spent in a ha-ha (a sunken ditch which acts as a barrier for livestock, without spoiling the view), chipping away at an old stone wall prior to its renovation. As chunks of limestone disintegrated under our trowels and beetles, toads and wasps found their habitats destroyed, I wondered how much damage Trust volunteers unwittingly cause. But a school worker dispelled any guilt. 'A lot of the best stones have been taken away by teachers,' he told us. 'They turn up in their garden walls.'

We were a mixed bunch: engineers, teachers, a school matron, a cook. But the shared sense of purpose and the hard outdoor work produced an immediate camaraderie, manifested mainly in an endless stream of puns. 'Get in there, you sod]' shouted Erica, a primary teacher, as she threw a large lump of earth into a barrow. After two days of using a mattock (a type of pickaxe used to loosen the soil) the word had yielded more puns than I thought possible. When I was caught in the face by a lump of mud, self-inflicted after too enthusiastic a blow, I was a 'mattockist'; Brad, a disc-jockey, accidentally chopped a worm in two in the 'mattocker of the innocents'.

The puns would have been appreciated by the Temple family, owners of Stowe for three centuries from 1593. It was the Temples who commissioned what was effectively England's first landscape garden, and filled it with temples, follies and arches, consciously evoking the world of ancient Rome.

The 750-acre gardens are described by the Trust as 'England's largest work of art' - it shames me to think that in five years as a schoolboy I barely even noticed them. Capability Brown was Head Gardener for a decade from 1741, and was married in the small church which still stands near the main house. His creations, and those of his predecessor, William Kent, are beautiful in themselves; but the gardens also stand as a monument to the radical Whig politics of a rich and eccentric family who used their money and influence to create a lasting shrine to their liberal beliefs.

The most obviously political monuments are found to either side of the Alder river, commonly known as the Styx. To the west, the Temple of Ancient Virtue is a rotunda containing statues of Homer, Socrates, Lycurgus and Epaminondas, all Greeks; the remains of Modern Virtue, nearby, once contained the headless statue of the Prime Minister, Walpole, a pointed and damning contrast between classical greatness and modern degeneracy.

Across the Styx, reflected in the water, the Temple of British Worthies holds busts of eight thinkers (Shakespeare, Milton, Newton . . .) and eight doers (Raleigh, Drake, Elizabeth I . . .), considered the greatest that Britain had to offer. A niche in the centre contained the head of Mercury, the god who would lead the souls of the blessed across the Styx to join Homer and Socrates in the 'Elysian Fields' opposite. Britain's heroes, in other words, were almost fit to be lifted to the level of the ancient Greeks; its contemporary leaders were not.

Behind the Temple of British Worthies is an almost illegible inscription to 'Signior Fido, an Italian of good extraction'; this 'faithful friend' and 'loving husband' is in fact a greyhound. Another monument to the Temples' eccentricity is the Gothic Temple, a triangular, turreted structure built high above a meadow and looking for all the world like a haunted palace. Originally the Temple Of Liberty, it represents the freedoms of Magna Carta and once contained the quotation over the door: 'I thank the Gods that I am not a Roman'.

'Is it haunted?' I asked Frank, the head gardener. 'Only by American tourists,' he replied. It is managed by the Landmark Trust and can be rented for (expensive) self-catering holidays.

The National Trust acquired the gardens in 1929 and is making efforts to restore them to the 18th-

century design; the work is expected to take another 50 years. We couldn't pretend that our week had made much difference - yet there was great satisfaction in seeing a task, however small, completed. When we returned to our puddling pond on the last day, the monk was almost invisible because the level was 2ft higher, and water was flowing over the clay and into the outlet which we had built up.

Finally, we all posed for a group picture on the massive heap of soil that we had dug. 'The earth moved for us,' said Erica.


Stowe Landscape Gardens: three miles north-west of Buckingham, nearest station Milton Keynes. The gardens are open during school holidays and at selected times during term (0280 822850 for details); admission pounds 3.50, family ticket pounds 9, NT members free. The house is open at certain times (0280 813650); admission pounds 2 including NT members.

National Trust holidays: details from Beryl Sims, National Trust Working Holidays, P0 Box 538, Melksham, Wiltshire SN12 8SU (0225 790290).

Conservation holidays: other organisations offering working conservation holidays include the following:

British Trust for Conservation Volunteers (BTCV) (0491 839766). Similar to NT projects but the accommodation tends to be more basic. Prices from pounds 28.50 for a week.

Working Weekends on Organic Farms, 19 Bradford Road, Lewes, Sussex BN7 IRB. Free board and lodging in return for work. Send sae for details.

Sunseed Trust, P0 Box 2000, Cambridge CB3 0JF. Desert reclamation project in southern Spain. Prices from pounds 49 plus travel for a 24-hour working week. Send pounds 1 for details.

Earthwatch, Belsyre Court, 57 Woodstock Road, Oxford OX2 6HU (0865 516366). Environmental and scientific projects worldwide for paying volunteers. Examples include counting rhino herds in Zimbabwe and archaeological excavation in Majorca. Projects last two weeks and cost at least pounds 800.

(Photograph omitted)