The Victorians' obsession with the exotic Lady's Slipper Orchid almost led to its extinction - until one wild example was discovered in North Yorkshire, as Lindsay Jennings reports.

THE only clue to its existence is the warden sitting in the sunshine to the side of a wooded footpath, knitting. Laura - it is her turn to be warden today - looks somewhat surreal, sitting in the countryside finishing off the sleeve of a multi-coloured wool jumper while she waits for visitors.

This site, near the border with Lancashire and Cumbria, is not widely advertised, but to thousands of botanists in the country nor is it a secret. Many will travel hundreds of miles to be here, to marvel at the beauty of one of the rarest flowers in Britain - The Lady's Slipper Orchid. A clue to the effect it has, is in the visitor's book next to Laura's bag of wool: "Wonderful to see, what a treat," one entrant has scribbled. "Amazing," writes another. "It's yellow - WOW!" an excited six-year-old has scrawled.

Laura is positioned a few metres away from her exotic charge so that those who have come to pay homage can savour their time with it alone, mostly in awe-filled silence. It is almost unnoticeable at first, nestled between two blocks of limestone, in the shade of a hazel tree and a holly bush. The second clue (after Laura) that there is anything to stop and examine lies in the slight wearing away of the footpath in front of this protected specimen, otherwise known as Cypripedium calceolus.

Ian Taylor, a botanist with English Nature, moves discreetly aside while I gingerly stroke the maroon coloured petals and peer at the distinctive yellow "lips," which are shaped like tiny delicate slippers, hence the name.

To my very ungreen fingers, I can only begin to imagine how this flower - only the second Lady's Slipper believed to be growing in the wild in Britain - is the subject of such obsession in the botanical world.

"This one is almost identical to the Yorkshire one, but its DNA suggests it's either Austrian or from the Pyrenees," says Ian. "We suspect that somebody put it there a long time ago, possibly even one of the Victorians. Most people just come and enjoy it because it's growing in the wild, even though they believe it's not British. But I think the real fanatics would find that a turn-off."

The Lady's Slipper Orchid has always had the ability to provoke adulation. The flower used to be found in abundance in the limestone areas of Yorkshire, Cumbria and Durham, but the Victorians wanted the species for their dried flower collections and for their own gardens and hounded it to the brink of extinction.

Says Ian: "They didn't just collect plants to grow in gardens, they used to exchange crest flowers in botanical exchange clubs. It was a bit like swapping Pokemon cards and they would get a different amount of credit for rare or difficult to find plants. Because the Cypripedium was rare and exotic it carried a lot of kudos. The problem was, they are quite difficult to grow, so the Victorians took them and planted them in their gardens and ended up killing them all."

By 1917 the species was declared extinct in Britain and so it remained until a single wild flower was discovered in a remote part of North Yorkshire in the 1930s. Although its position was kept a secret, by the 1960s it once more became threatened by collectors. And when someone decided to chop a piece off the plant for their collection, it prompted the late Edgar Milne-Redhead, of the Botanical Society of the British Isles, to set up the Cypripedium Committee. The aim of the committee, which included representatives of Nature Conservancy (now English Nature), The Yorkshire Wildlife Trust and the Yorkshire Naturalists Union, was to protect the flower in North Yorkshire and see the Lady's Slipper in abundance across the North again.

Since then, two other specimens have survived in cultivation at Ingleton Woods in North Yorkshire and in the grounds of Hornby Castle, in North Lancashire.

But it is the North Yorkshire orchid which causes the most excitement. Its site is guarded 24 hours a day by a warden when it is above ground, from mid-April to late August. Its visitors are strictly limited and even Ian Taylor, who is chairman of the Cypripedium Committee, has never seen the flower, although he visited the site for habitat management six years ago. The committee itself has not visited for 17 years.

"We call it 'The Wild One'," he says fondly.

"We guard it not just because people will steal it, but because if a lot of people turned up they could quite easily stand on it or dump their rucksacks on it by accident. We ask the botanical community not to visit and we refrain from going to try and prove a point that we're serious about it.

"A lot of these people are reasonable. They don't tell anyone and they never go. But some of them just have to have a look, and the warden on site is there to dissuade them. It's a temptation that some people can't resist, and they can get quite ... enthusiastic. They can be quite abusive at times, quite aggressive even. But we've never had anyone attack the warden yet, or the plant. I can sympathise with them wanting to see it because it's a beautiful thing and it is the one which has the history about it."

'The Wild One' did not flower from 1935 to 1958, apart from a single offering in 1943. But with careful management, its flowering capability has grown. 1999 was a bumper year with 23 flowers. Lady's Slipper is a fastidious breed and does not like her surroundings too shady, nor too sunny, and is at the constant mercy of slugs, hungry rabbits and, of course, the fanatical botanical.

Since the mid-1980s, and as part of English Nature's Species Recovery Programme, scientists at the Royal Botanic Gardens at Kew have successfully artificially pollinated the wild plant to produce seeds. The plants normally only germinate with a specific fungus, but they have successfully used a medical solution, designed for use in caring for premature babies, for germination.

Since 1989, about 200 hundred specimens have been planted at 12 sites in the wild, but only one has flowered. After years of painstaking work, the consensus is that the fungus they artificially replicate not only helps with germination but, in the wild, helps protect the plant from other funguses and from the elements of nature.

"I don't think we've got the conditions right," says Ian. "We're having to guess what the plants want and they can't say what they want - except by dying. If we could create the fungus, I suspect we might find a sudden increase in our success rate. If we could get the conditions right, and the fungus, I think maybe in 15 to 20 years we might have some reasonable populations in place. It's certainly not going to happen any faster than that".

The frustration for the 100-plus people who have been involved in this long-running project must be vast, from the wardens and amateur orchid growers who nurture the seedlings at home before planting in the wild, to the scientists at Kew. Just when they think they have the conditions right, the plants stubbornly refuse to flower, or die. Will the exacting Lady's Slipper ever give them what they seek?

"It is a challenge," says Ian, smiling.

"A lot of other challenges are to do with habitat management, but not with the Lady's Slipper Orchid. You can do that until the cows come home and nothing will happen, it will just sit there in Yorkshire, doing nothing. The challenges with the Lady's Slipper are scientific with a bit of mystery thrown in. Just when you think you've got it right, you find all the plants have died.

"But people stay with it because it's just outside their reach. It has that characteristic which makes it just about unattainable."

Walking back along the footpath, Laura puts down her knitting and holds up the visitor's book for me to sign. I pause for a second, thinking of how healthy the Lady's Slipper looked, with her eight flowers, for such a delicate species.

"Robust," I write. "...and beautiful."