A series of events is being staged to mark the 40th anniversary of the publishing sensation that was Masquerade, a picture book that promised hidden treasure to the person who could solve the clues hidden within its pages.
It's a familiar tale: treasure-hunters racing to decipher clues from a mysterious book that will lead them to buried gold.
But this particular hunt, and its waiting treasure, was no work of fiction - even if the creation that inspired it was.
In 1979, artist Kit Williams published Masquerade - a storybook decorated with paintings whose intricacies held clues that would lead the successful sleuth to an 18-carat golden hare.
A phenomenon at the time, the book sold more than a million copies and sparked a worldwide hunt for the gold.
Forty years on, Masquerade retains an army of fans who have handed down their passion for the book, and their memories of the frenzy that gripped the country.
Readers were addicted, with treasure-hunters driven as much by being the first to solve the riddle as the value of the jewel-encrusted hare.
Countless lawns were dug up, and fed-up landowners put up signs warning off fortune-seekers. The book was even cited in divorce proceedings.
But when the golden hare was finally unearthed, three years later in a park in Bedfordshire, the story was far from over.
The scandal behind its discovery shocked fans around the world, and turned Williams into a recluse.
Ironically, it was a story that could have come out of a work of fiction.
The hunt begins
Masquerade follows the journey of Jack Hare, who loses a jewel he has been entrusted to deliver from the moon to the sun.
And the real-life treasure was fit for a fairy-tale, having been hand-beaten by Williams himself. It was valued at £5,000 - although it would eventually prove to be worth much more - and inset with ruby, mother-of-pearl and moonstones.
This golden hare caught the imagination of millions, yet for nearly three years its hiding place was known to only two men.
Setting off one night in August 1979, Williams was accompanied by a single witness chosen by his publisher Tom Maschler - the television host Bamber Gascoigne.
At a precise spot on the common, Williams and his famous witness buried the hare, which was sealed in wax and placed in a ceramic case to evade metal detectors.
Upon it was the engraving: "I am the keeper of the jewel of the Masquerade, which lies waiting safe inside me for you... or eternity."
Having witnessed the burial, Gascoigne was to provide the final flourish, emptying over the hare a fresh cowpat from a Tupperware box.
The perceptive reader would be led to this location - selected by Williams years before while on a picnic with his then-girlfriend - by unearthing the complex clues in the paintings.
But the paintings' detail allowed for almost as many interpretations and theories as there were fans.
The book was an instant success, as readers from across the world raced to solve the mystery.
An airline even sold transatlantic Masquerade tickets, which came with a free spade on arrival.
"The first edition sold out within two days or something like that," Williams recalled in a BBC Four documentary, The Man Behind the Masquerade.
"They were reprinting so fast. It became a sensation in a way, that it moved so fast."
Williams, until then a little-known artist, was thrust into the spotlight.
He embarked on a publicity tour of the United States, appeared on talk shows in the UK, and was inundated with requests from fans desperate for help.
Soon, more than 200 letters were arriving at his house daily and Williams had to read every one.
"I was unprepared," he said. "It really got out of hand really quickly."
Among the guesses posted through the artist's letterbox were more unsettling submissions, among them severed rubber hands.
Rallying round, Williams' neighbours in his Gloucestershire village began to deny any knowledge of him to inquisitive fans.
Among the golden hares and red herrings, only one theory led to the correct solution - and the golden prize.
To complete it, the puzzler had to draw a line from the eye of each of the animals in the 15 paintings through hand or paw to a letter in the border.
This revealed a word or phrase which, put together, formed the crucial clue.
It read: "Catherine's / Long finger / Over / Shadows / Earth / Buried / Yellow / Amulet / Midday / Points / The / Hour / In / Light of equinox / Look you."
When arranged in verse, the acrostic of the first letters spelled out "Close by Ampthill".
It gave Masqueraders their final, essential pointer towards the Bedfordshire town, near which Williams had lived years before.
The burial spot was where Williams knew the shadow of Catherine of Aragon's cross fell on the spring and autumn equinox - meaning it would point to the right place on the right day.
It took nearly three years for the code to be cracked, by physics teachers Mike Barker and John Rousseau - but the treasure was ultimately to elude them.
By early 1982, Barker and Rousseau had arrived at what Gascoigne later called "the most perfect solution" to the puzzle.
They had made their breakthrough with the help of an additional clue published in the Sunday Times in 1981.
That hinted to them that fingers and toes might hold the key to the puzzle.
Remembering the introduction to the book - "To solve the hidden riddle, you must use your eyes" - they realised that a straight line drawn from each animal's eye, through its paw, pointed to a letter in the border. Put together, these letters spelled out a word.
It was the book's eighth painting, which revealed the word "Amulet", that convinced Barker and Rousseau they had done it.
From there, they reached "Close by Ampthill", found the park and identified the monument.
In January 1982, Barker visited the park to dig for their treasure but, without the precise instruments to calculate its resting place, was to return empty-handed.
But as the two men resolved to wait for March's equinox to point them to their prize, the golden hare squirmed from their grasp.
They were beaten to the find by a reclusive puzzler called Ken Thomas, who shunned the publicity that came with solving a mystery that had captivated the world.
He was filmed with Williams as he freed the hare from the wax case, but later insisted on covering his face with a scarf and would only be interviewed from behind a screen. He refused to exhibit his treasure.
Unable to share in the joy of his discovery, Masquerade fans grew suspicious of Thomas and, later, Williams, with some even suggesting he had conspired to cheat them.
After years of searching for hidden clues, they saw another in an anagram of Kit Williams: "I will mask it".
The artist, however, shared their doubts over Thomas, realising he had not solved the full puzzle but uncovered the gold's location by other means.
It was not until 1988 that a newspaper finally uncovered the link between Thomas - revealed to be a pseudonym - and Williams' ex-girlfriend, who had remembered their visit to Ampthill years before.
When Thomas's company Haresoft collapsed he was forced to sell the hare at auction to raise money.
That led reporter Frank Branston to look into the company, the director of which was named Dugald Thompson - not Ken Thomas.
Thompson had previously been in business with a man named John Guard who was, at the time of the discovery, living with Williams' ex-girlfriend.
Williams, speaking later to the Sunday Times, said he felt "conned" and knew from the start that Thomas had not truly solved the puzzle.
The hare, having fetched £31,900 at auction, passed into private ownership and disappeared from public view for more than 20 years.
Williams, the man whose imagination had spawned the phenomenon, did the same.
He had grown disillusioned at his artistic reputation being reduced to that of a puzzle-maker, and having seen his creation corrupted.
"At the beginning he was quite grateful to me for having fostered this creature," his publisher Tom Maschler told BBC Four.
"But later he was quite resentful at times because I had destroyed his peaceful life. And he's right - I did."
Williams never stopped painting but put on only private shows to which select buyers were invited.
It was not until 2009, as his most famous work neared its 30th anniversary, that he returned to public life with an exhibition of some of his 300 intervening works.
After retreating from the limelight for many years, Williams agreed to take part in a Radio 4 programme to mark Masquerade's milestone.
The broadcast was heard by the owner of the golden hare, by this time resident in the Middle East, who offered to display it at Williams' exhibition.
The artist's reunification with his creation was filmed by the BBC in The Man Behind the Masquerade.
Williams confessed he was overwhelmed to see his youthful creation again, and remained proud of what he called "an apprentice piece".
"I made it because I was almost no-one, going nowhere," he said.
"I made it thinking 'this is something rather special', and it turned out that way."
Its mystery has been solved and its treasure found, but the fascination of Masquerade lives on.
For its fans, Ampthill has become a place of pilgrimage, and there remains a keen interest in the book in the town.
Masquerade40, a series of events launched on the equinox, will run through the year to mark the anniversary, and includes walks and craft events at the burial spot.
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A painting by local artist Karen Mangold, Close by Katherine's Cross, will be unveiled and Mark Jeoffroy has written the short story Jack's Parade, a continuation of the book.
Stephen Hartley, of Masquerade40, said Williams' book had been woven into the town's history.
"It lives on, and has become part of local folklore. The Ampthill library has its weather vane as a hare, and there is public art incorporating hares," he said.
"Younger people in the town know about the hare, but I think it has sidestepped them to a certain extent.
"Masquerade40 will bring it to a new generation."