WHAT started out as an exercise for schoolchildren in a tiny village near Thirsk has become its most famous landmark.

Kilburn's White Horse is "stabled" high above the picturesque village and, although not the only such horse, it is the largest in England.

It stands 900ft above the Vale of York.

It was carved on Roulston Scar in the 1850s, the idea of Thomas Taylor, a native of Kilburn, who had left his home to join the thriving provisions business of his brother, William, in London.

Thomas came across some white horses cut into the hills in Berkshire and thought it would be a grand idea to have one in his homeland. He contacted his friend and village schoolmaster, John Hodgson, who was also a land surveyor, and sent him his drawing of the idea.

A copy of that plan with all the measurements - one of only two, the other being lodged in the Yorkshire Museum in York - has been handed down through generations and is now in the hands of Paul Hodgson, who moved back to Kilburn from Borrowby after a serving for many years in the army.

"Our family have lived in the area for generations. I believe that John Hodgson was my great, great, great uncle. It must be fate that I came to settle here," said Mr Hodgson.

The White Horse will never go thirsty as Mr Hodgson's land at Acre Hill Farm is situated on nine natural springs and the water is now bottled and sold as Chilburne Spring Water.

"Kilburn is mentioned in the Domesday Book and spelled as Chilburne, meaning cool spring - hence the name of the company," he explained.

He came to the farm in 1991 when his wife, Alison, became terminally ill with cancer. She was senior clinical medical officer for Thirsk and district and died in 1993.

"She didn't know about the water development before she died. Although we knew that we had a lot of water, can you imagine trying to sell bottles of it to Yorkshiremen at that time," he said.

But, back to the horse, which stands high above the farm.

Taylor's plan is detailed with scribbled measurements and the schoolchildren helped plot the 304ft length and 228ft height of the horse, which can be seen for miles around.

Farmers cut clods of turf and the outline was covered in lime.

Nowadays you can climb alongside the mare by a steep set of steps from the bottom or approach it from above on a walk from Sutton Bank visitor centre.

The site might be one of the best to show off a hill carving, but in other respects it is not very suitable. The slope is extremely steep, the underlying rock is grey-coloured and unstable sand limestone, unlike the more stable and whiter chalk in the South of England.

So the horse's coat needs regular "grooming". In days gone by, local farmers helped with the task.

Nowadays, to stop the horse from becoming overgrown with weeds, its whitening is monitored by the White Horse Association, which was set up at the Forresters Arms, down in the village.

"During the war years, the military ordered that the horse be hidden from view with camouflage netting and turf. It was thought that enemy aircraft might use it as a marker guide to the bomber stations dotted around the area. It was not uncovered and whitened again properly until after hostilities ceased," said Mr Hodgson.

When he first moved to Kilburn, he could see the feet of the horse from his farm. Nowadays, the forest has grown, blocking the hooves and lower legs from view.

Many a practical joke has been played on the horse over the decades. It is assumed to be a white mare, but a favourite trick is to change it into a stallion. It has even been turned into a zebra and more recently a rider was placed on its back.

"I have offered to construct a foal alongside the mare, but landowners, the North York Moors National Park Authority, don't approve of the idea," Mr Hodgson added.

Visitors from near and far are attracted to the horse and although there are large notices warning people not to walk on it and damage its surface, many still do.

"One of the most popular things for large groups is to see how many people can actually sit on the eye - I think 26 people is the record," added Mr Hodgson.