According to legend, the Holy Grail could be hidden in Glastonbury, in Rosslyn Chapel in Scotland or Malta. But, as Lindsay Jennings discovers, it could be buried in Yorkshire.

ELVIS does his shopping in the Wal-Mart in Caro, Michigan in the US. Marilyn Monroe has had a face swap and is alive and well treading the boards on the West End stage - a serious actress at last. Oh, and the Holy Grail is buried in Yorkshire.

Everyone loves a conspiracy theory - a smattering of myth mixed in with our latter day obsession for a good old detective story. But while we have as much chance of seeing Elvis in Wal-Mart as we do of seeing Marilyn singing All That Jazz in Chicago, what about the Holy Grail? More importantly, what about the possibility that it could be hidden in Yorkshire, buried in a field for centuries at the spot where the secretive order, the Knights Templar, is said to have built a stone church?

The legend of the grail varies greatly. To some, it is the sacred vessel Jesus filled with wine at the Last Supper and passed to his disciples. To others it is the cup Joseph of Arimathea used to collect the blood of a dying Christ before fleeing to Glastonbury where it was guarded by his descendants for centuries. To thousands of conspiracy theorists and fans of Dan Brown's novel The Da Vinci Code, it is not a cup at all, but evidence that Jesus Christ had a child.

From the Grail's first appearance in an unfinished poem written by the Frenchman, Chretien de Troyes in 1180, some authors have emphasised the Christian element and others the mystical, with a smattering of Welsh, Celtic and Irish lore blended in. The grail could be at Rosslyn Chapel, in the Scottish borders, in Glastonbury, or even in the Cathedral of Valencia in Spain, which is home to the Holy Chalice, a 17cm-high cup made of red agate and dating between 4th century BC and 1st century AD. Yorkshire has not figured greatly on the grail radar - until now.

According to former vicar and best-selling children's author, Graham Taylor, Rosslyn is a red herring, Glastonbury a goose chase and Spain a smokescreen. The reason the grail could be in Yorkshire, he says, is to do with the area's Templar connections.

The Knights Templar were formed after the first crusade in around 1120 in order to capture the Holy Land and protect Christian pilgrims en route to it. It was during this time the knights are said to have dug beneath their headquarters, the Temple of Solomon, in Jerusalem, and discovered ancient knowledge in the form of artefacts said to have come from Egypt or, as some believe, the lost city of Atlantis. One of these is said to have been the Holy Grail.

The soldier monks, as they were known, became extremely rich and powerful, spreading themselves across Europe and amassing swathes of land on which they built preceptories - a combination of farmsteads and monasteries. There is still evidence of their existence today in the names of roads and farms across the country and they were believed to have ten preceptories in Yorkshire. There was a vast Templar estate just south of Temple Newsam House near Leeds and preceptories at Penhill, West Witton, in Wensleydale, and at East Cowton, near Northallerton.

But the Templars' luck changed when in the early 14th century, King Philip IV - who was envious of their great power and wealth - charged the order with heresy and immorality. Many Templars were tortured and burned at the stake.

Eventually, the Pope officially disbanded the knights and those remaining are said to have fled to Scotland and Portugal, two nations which refused to accept the Pope's authority at the time. In England, many Templars were sent to the abbeys to do penance.

But did they leave their most precious cargo, the Holy Grail, hidden behind somewhere, or did they take it with them?

On a bitter cold winter's day, with the wind whipping around our ears, Graham leads the way up the pathway to a church built at the beginning of the last century. The church contains some unusual stonework said to have been taken from the ruins of a nearby Templar church.

"All around the church there are older pieces of stone," says Graham, pointing to an ornate lintel halfway up the wall of the building.

"The church also points to the old Templar church on a north-south line. Why would the Templars have such an interest in such a remote part of the empire and build a church around here? I think they were here because they were looking after something."

But the old Templar church apparently lies on a popular pilgrimage route, which could explain why they chose this remote part of the Yorkshire countryside. The Templars were known for their modern banking system which allowed pilgrims to stop off at preceptories to collect money against funds they had deposited at Templar strongholds in Europe. This meant pilgrims weren't carrying huge sums of money throughout their journeys.

"This area was the M1 of the religious superhighway of the Dark Ages and we don't appreciate in the North how much was going on spiritually in this area," says Graham, who believes this remote part of Yorkshire is also used to holding secrets. Around the time of the Templars, he says the 15 landowners of the area were exempt from paying tax.

"My theory is that people here were told they were tax free because they maybe knew something," he says. "I believe places like Rosslyn and Glastonbury are red herrings."

He is also convinced that the modern church down the road holds another secret. A piece of stone which was chipped away from Christ's sepulchre, his tomb, is said to have been buried within the walls of the church. Graham says he found evidence of this in an old minute book he discovered while he was a vicar.

"It was an old dusty minute book and inside it, it said the stone was brought to the area by an archaeologist in the early 1900s," he says. "I believe it's been embedded into the wall."

But Graham believes that, if the Holy Grail exists, then it will be under the site of the old Templar church, in a nearby field. We drive up to it. It is ordinary looking, a hill covered in grass and nothing more.

"It's best to keep the exact location a secret because I know there are people out there who are obsessed with finding it," says Graham enigmatically.

But this area has remained undetected to the modern day grail hunters so far. There is barely any mention of it on the internet, aside from the odd reference to its Templar connections. Graham says he heard about the grail theory through local people.

"There is a legend in these parts that it is here. One of the old guys, who died, talked about the field and what was there. You start to hear these stories and you wonder if there's something more to it."

According to Graham, however, the land has never been excavated, and nor is it likely to be. "No one knows the history behind it. All we know is that it used to be the site of a Templar church on the outskirts of an empire on a pilgrim's route," he says.

We drive back to his home near Scarborough. Over tea, we talk about Dan Brown's book (pure fiction, he says) and the stonework incorporated into the modern church. Does he really believe the grail is in Yorkshire?

He smiles. "Put it this way," he says. "As someone who's researched myths and legends, it's an ideal hiding place for the Holy Grail. I wouldn't be surprised if it was buried in the field. But then it could be in Malta..."