The British royals were in Thailand on behalf of Queen Elizabeth to honour the auspicious fifth-cycle, 60th birthday of King Bhumibol Adulyadej, Rama IX. Their largely uninvited media retinue doubtless followed because they felt there was simply nowhere else in the universe worth being, which is fair enough.

Local reporters and photographers strained valiantly to prise open small cracks in the heaving, unyielding wall of foreigners relentlessly recording the couple's every word and gesture. At the Huay Hong Khrai Agricultural Research and Development Study Centre near Chiang Mai, an unfortunate Thai photographer finally succumbed to the spirited jostling - and end ended up in the centre's reservoir among the fish. "One gone," commented Prince Charles wryly as he heard the splash.

Nobody asked the fish what they made of all the excitement, but the heir to the British throne said he would like to return in a few years' time to see how everything was progressing. Officials also made certain he departed with three 1.6 kilogram melons to sample on the flight home.

Earlier in Bangkok, a burly Australian photographer was asked about his first impressions of the Thai capital. "Much cleaner than I'd expected," was the unlikely response. Well, it's no Singapore yet - mosquitoes are still occasionally allowed in witho ut visas - but it is definitely becoming rather spick and span.

Aided by some altruistic and very energetic members of the private sector, the Bangkok Metropolitan Administration under charismatic and popular Governor Chamlong Srimuang has in fact wrought some thing of a green revolution.

Gone are the days when trees would be planted and only the bamboo poles supporting them sprout leaves. Busdevouring potholes are slowly but surely being taken out of commission. And street-sweepers have recently been elevated to lofty folk hero status - when the general public was asked to nominate their favourite broom wielder in March, postcard nominations poured forth in thousands.

It is often said, with some justification, that Thailand is a one-city country containing few large provincial towns and thousands of small villages. Park starved, densely built with chaotically heavy traffic, Bangkok is certainly like nowhere else in the country. Its citizens' penchant for high walls adds a flavour of secretiveness to countless to countless dark, narrow lanes, though incessant noise, garish splashes of colour and people absolutely every where help relieve any hint of the sinister.

But the city's pan-flat setting betrays no hint of the rolling hills of the north, the precise gridwork of central plain rice fields, arid expanses in the northeast, or any suggestion of the south's lush tropical vegetation. Representative or not, Bangkok is, if nothing else, a city of surprises.

Unrural to a fault, it nevertheless has, right in its heart, a farm - complete with fish ponds and rice fields - Sources both of the most traditional of Siamese staples. This farm also boasts something far from traditional - a dairy herd. More surprising still, the farm is surrounded by a moat and guarded day and night by hand-picked troops. Could this by any chance be because it happens to supply the most coveted rice grains in all the land?

There is in fact nothing in the least bit secret about the farm. Commuters traveling past on buses can see the 50 or so cattle through recently repainted railings, and perhaps check the breeze by glancing up at the wind-driven water pump tower - a slightly incongruous landmark for a palace. Yes, it's a palace with a farm.

Dusit Palace's grounds occupy slightly more than a square kilometre and contain the Chitralada Villa, main residence of King Bhumibol Adulyadej and Queen Sirikit. They are also home to countless ot her structures, including a distinguished school and stables accommodating the herd of eleven royal elephants (six of which have been ceremonially elevated to the rank of white elephant). But it is the farm and the host of agricultural projects alongside that are probably the more telling indicators - hallmarks, some might venture - Of the present reign.

There are more than 1,000 royally initiated rural development projects in Thailand that touch on an estimated 4,000 villages in 56 of Thailand's 73 provinces. Many of the Royal Chitralada Projects at the palace are experimental; all are intended to be exemplary.

The Chitralada's attractive wooden rice mill, constructed in 1971, purchases samples of the crop from places such as Ang Thong, Ayutthaya and Saraburi as well as more marginal provinces. Detailed information is then compiled on such things as prevailing market prices, the proportion of broken grains and husk content - all useful barometers of basic economic wellbeing in a rice-producing nation. Valuable research has also been conducted at the palace rice storage.

About 30 per cent of unmilled rice by weight is husk. The Chitralada projects include a solid fuel substitute made from this byproduct compressed either on its own or in a greener form with a 30 percent mix of decomposed water hyacinth - a troublesome waterborne weed frequently responsible for clogging up waterways.

The palace's 2.5 rai of paddy fields cater to some 40 experimental varieties of rice intended for conditions varying from arid upland to flooded lowland plain. Each year in May, Chitralada rice, which has been cultivated since 1961, is used in the Royal Ploughing Ceremony, an elaborate Brahmin ritual revived in 1960 for the start of the annual rice-planting cycle.

The popular ceremony is held at Sanam Luang in view of the Grand palace, and attended by farmers from all over the country. After the ceremonial sowing, spectators fall over themselves in an undignified scramble to gather up as many of the treasured specks as possible for inclusion with their own seed grain.

Considerably larger quantities of rice can, however, be found at some 800 Royal Rice Banks set up all over the country. The first was established in 1970 at Pa Pae, a village in the northern province of Mae Hong Son. Needy farmers can borrow seed rice from the bank when necessary, and repay it with interest after the harvest. In this way, the bank's rice 'capital' grows.

Sheets of inexpensive polyethylene sheeting held together with string and clothes pegs bind a three-part mixture of sand, coconut husk and coconut dust. Add a spoonful of fertilizer per plant plus just enough plastic-retained moisture and reap tomatoes , lettuce, cabbages, Chinese cabbages, broccoli, asparagus, marigolds, and who knows what else - after only seven months, they're still finding out.

The Chitralada Dairy Plant Project includes a herd that has mushroomed from six milch cows donated in 1962 to about 50. The dairy exists essentially for demonstration purposes for the 1,000 or so farmers and students who visit most weeks. As with Princ e Charles in the north, foreign dignitaries are also often show round. Among the more recent was Prince Hitachi, younger son of Emperor Hirohito of Japan, and his wife, Princess Hanaka.

The dairy - which is about to be complemented by a cheese-making plant - buys in 90 per cent of its raw milk from producers such as the Nong Phor co-operative in Ratchaburi Province. About five per cent of the dairy's output is dried following construc tion of a powdered milk plant in 1969. Some is compressed for distribution in tablet form. Daily production runs as high as 9,000 225ml bags of pasteurized milk distributed to some 40 schools in the neighbourhood.

Not far from the dairy - across one of the teeming fish ponds, in fact - is a 27-year-old demonstration forest covering some three rai and containing no fewer than 1,250 tree species. This well established and large arboreal bank is supported by a much more recent project which aims to preserve and hopefully propagate through tissue culture rare plant and tree species. The original five species - which included a special jack-fruit found in one of the old palaces - have already been increased to 20 by the unit's staff of five.

Another of the newer of the Chitralada projects is the two-year-old candle factory. It produces nearly 40 exceptionally fine and ornate one-metre, candles each year for donation by the palace. One of the best know of these enjoys pride of place in the colourful procession during the famous Candle Festival in Ubon Ratchathani at the start of the Buddhist lent in late July.

The small factory also produces fine quality pure bees wax candles of various sizes for use in royal ceremonies. Their sharply moulded profiles contrast strongly with the old fashioned hand rolled versions still produced in the Grand Palace. Space in the candle factory is shared with a small team of artisans who painstakingly restore ornate items of gilded and glass inlaid ceremonial furniture.

The Chitralada projects are very clearly not intended to dazzle with high technology. They are for the most part simple, constructive and accessible - many ingeniously so. As Bangkok leaps breathlessly into the future, the some-what unexpected farm in its midst serves as a useful and gentle reminder of the historically bountiful countryside where the main wealth of the kingdom - and overwhelming majority of its people - Still lies.

If the main aims are to encourage self-reliance and demonstrate that good ideas - especially those which feed people - need be neither extravagant nor technologically prohibitive, then the Chitralada projects are surely creditable.

And, come to think of it, maybe Bangkok isn't really so full of surprises afterall.