In Siam of the past and Thailand of today, the discovery of a white elephant is considered a very auspicious sign for the ruling king, and ownership of such beasts is his prerogative. Anyone who thinks they have seen a white elephant must notify an official - today someone at the Ministry of Interior - who in turn informs the Bureau of the Royal Household. Representatives from that august body conduct an examination to decide if the animal bears the characteristics of this special and most noble creature.

There are four classes of white elephant; whether, and where, a particular animal belongs is decided upon based on an arcane set of standards that includes, but is not restricted to, colour. (In fact in Thai the animals are called chang pheuk, albino elephants.) The colour of the elephant is assessed; it's not actually white, but generally pale and mottled in white, yellow, black, red, and grey tones; the highest class of white elephant is lotus bud pink.

The eyes should have white or pink rims, the irises a blue or pink tinge, though jet black is best of all. Asian elephants have two bumps on their foreheads (African elephants have only one); these bumps should be so pronounced that a man can lay his neck down between them. The beast's tail should hang straight, and it's best if the hairs on its tip touch the ground. The ears should touch when pulled together across the eyes, and the toenails should be light-coloured, either red, white or pink; it's most auspicious if the pachyderm has 20 toes. The trunk should be long and strong, and the patterns of hair along the back and head are examined minutely; three hairs emerging from a single pore is particularly fine.

Also important is the creature's personality. Does it betray its intelligence by running ahead of the herd to bathe first, before the waters are muddied by its companions? Does it choose grass tufts carefully, swishing them to either side before consuming them, thus discarding insects? Through such complicated judgements is the class of the white elephant decided.

In past times these lucky leviathans seem to have lived a life of consummate luxury, if the writings of the Portuguese Jesuit Fernao Mendez Pinto are any indication. His 1554 account of his visit to Siam some years earlier relates that he had been privileged to witness the procession of a white elephant through the city of Ayuthaya; it was adorned with a gold and silver saddle cloth and accompanied by 160 horses and over 100 elephants, many ridden by Siamese nobles. The entire procession froze when the white elephant paused, and its urine was collected in a golden vessel. The occasion was a visit to the river, where the royal pachyderm partook of the waters behind a screened bathing pavilion.

It is not surprising, then, that the first flag of Siam - in use from 1816 to 1917 - featured a white elephant on a red background; it was adopted during the reign of Rama II after he came into possession of a third white elephant, which joined the two he already had. The current king, Bhumibol Adulyadej (Rama IX), a worldly man, has six stables in his palace grounds in Bangkok where 111 elephants are housed, six of which have been through the Buddhist and Brahminic ceremonies conferring on them official white elephant status. The grand poobah of these is Phra Savet Adulyadej Pahon, a huge bull who is considered one of the finest white elephants of the Chakri dynasty; he is known for his proud and independent spirit. His most illustrious predecessor was Phra Savet Worawan, the pride of King Chulalongkorn (Rama V); it is fitting that these two most beloved and popular kings of the dynasty are associated with two most impressive and magnificent white elephants.

Modern royal elephants are not as coddled as they were in days of yore; they are under the care of a royal veterinary surgeon, who, with the king's permission (which must be granted in all matters relating to these venerable animals) has reformed their care. They have more exercise than was true of their predecessors of days gone by, being ridden by their mahouts (except for Phra Savet Adulyadej Pahon, who is too exalted to be mounted), and are given the choicest grasses and fruits. The royal vet has also apparently tried to doctor bananas with vitamin and iron pills to boost their health, for a spoiled elephant is a delicate one; this ruse was successful only once, and thereafter the intelligent creatures refused all adulterated fruits. This means they have an annual injection, a black day for the royal vet as the elephants trumpet their outrage at his ministrations.

In a perfect blending of tradition and modernity, Thai scientists are engaged in an ambitious ten-year project to clone a white elephant that was revered over 150 years ago, during the reign of Rama III.