Along the rough track that climbs from the beach to the homestead, Andrew "Lord Percy" Martin left signs bearing hand-written snippets of his favourite verses during more than three decades, often alone, on the wild and isolated Middle Percy Island. Contemplation is a recurring theme. "If you stand very still in the heart of a wood," begins one, "you will hear many wonderful things ..." And another: "What is this life if full of care / We have not time to stand and stare ..."

Martin had no shortage of time, and in the end it was excessive contemplation - not of nature but Old Testament prophecy - that would lead him horribly astray. But as the ute carrying us to the homestead grinds on up the track, it's easy to understand how the eccentric Englishman, and others before him, succumbed to the enchantment of Middle Percy.

Part of the Northumberland group, 70 nautical miles south-east of Mackay, it's a stunningly beautiful place of icing-sugar beaches and wooded hilltops - a Robinson Crusoe island rising from the indigo depths of the Coral Sea. Although only a day or two's sail from the southern Whitsunday islands, the 1657-hectare paradise is rarely visited except by cruising yachts and has never been exposed to tourism.

First charted by Matthew Flinders, and named after the Duke of Northumberland (who later cruised the area with his courtesan, the "scandalous" Lola Montes), Middle Percy was visited by Errol Flynn and, in 1932, by the Australian writer Dora Birtles, who captures its allure in her classic, North-West by North: "... perhaps the savage earth, its receptivity not dulled by the beating about of many passions, not asphalted over by events, keeps its earth memory fresh, still haunted by actions that would have died away in a civilised place long before."

Until 2001, when it entered a dark period characterised by its present custodians as "good versus evil", Middle Percy was one of the last remaining leasehold islands off the Queensland coast, bound to a tradition of providing fresh water and supplies to passing seafarers. Leaseholders - including Martin, the self-exiled son of aristocrats who took over in 1964 - also helped mariners in trouble and assisted with emergency repairs, although towards the end it was more often Martin than his visitors who needed rescuing.

In 2010, when Middle Percy was made a national park by Queensland's Bligh government, the then-leaseholders - Andy Martin's cousin, Cathryn Radclyffe, and her partner John Morris - became the managers of a portion (17 per cent of the island) known as a conservation park. It includes the homestead and land extending down to West Bay, the palm-fringed anchorage where Radclyffe and Morris collect me and my sailing companion in their old 4WD.

Crouched on the ute's tray as it nears the homestead, we hear the first bleats and clucks of Radclyffe's free-ranging menagerie, cut through by the shrieks and squawks of cockatoos and parrots. Radclyffe first came here from England to visit her "mysterious Uncle Andy" as a young woman; now, 57 and grey-haired but still agile, she jumps from the cab and bounds ahead to open gates, scattering goats and chooks.

Rebuilt over generations, the homestead is set on high stumps and ringed by sweet-smelling fruit trees. On the open veranda, Radclyffe serves tea and begins her wandering account of the last few decades. Much later, as we bump back downhill to the yacht, I wonder dazedly where this strange tale should begin.

With Uncle Andy's descent from rakish adventurer to Mad Prophet, convinced that God was speaking directly to him? With his rush back to England in 1996 to "save" Britain from its collective sins? Or perhaps slightly later when, despairing over Princess Diana's failure to rise from the dead and accompany him back to Middle Percy with her two sons, Martin recognised himself as a "false prophet" and prepared to be annihilated by his Maker?

Or the day soon afterwards, in its way almost as apocalyptic, when a huge Australian with a mohawk and glow-in-the-dark tattoos tracked Martin down in an English village and set about parting him from the lease to his beloved tropical island?

Inevitably, of course, there's only one way to start a story that opens in paradise and ends, at least for Andrew Charles Martin, in something close to hell. And that's at the beginning.

Martin first laid eyes on Middle Percy in 1964 while sailing north on his yacht, Southern Maid. It's likely he'd heard about the island through publicity it attracted the year before when a group of London-based Utopians - calling themselves the New Island Movement - sought to buy the lease for £A15,000. But as the group bickered internally over how its proposed Shangri-La should be run, Martin dropped anchor in West Bay, met the White family - who'd farmed sheep there for 43 years - and bought the lease himself.

The Eton-educated son of a socialite and a British Army general, Martin - then 37 - was a tall, powerfully-built figure who'd represented England in the pentathlon at the 1948 Olympics. He later left his wife, son, and two stepsons in Devon, where he owned two dairy farms, to roam the world. Cathryn Radclyffe isn't sure why: "For some reason, he just decided to travel ... he wanted his family to join him on the island, but it was too remote for them. Eventually they divorced ... the boys came to visit him in later years, but sadly there was always ill-feeling between them and Andy." (In a 1996 article in a British newspaper, Martin's eldest stepson, Andrew Thorman, called him a "bastard" who'd abandoned his family.)

In his early years on Middle Percy, Martin - who rarely appeared in anything but his trademark bathers - abandoned grand plans to "develop" the island and sell it for a handsome profit. "He told me he was initially going to sell it to some rich American," says Radclyffe, "but then he fell in love with the place." Martin developed gardens, kept bees, farmed goats and ran a cottage industry supplying fresh produce to cruising yachties.

Back then, he got his mail and supplies via a stores boat that arrived fortnightly to service the lighthouse (automated in 1986) at Pine Islet, just offshore from West Bay. On the shore of the bay, he later built the now famous "Percy Hilton", a rustic A-frame structure where visitors can sleep overnight, leave mementos of their vessels and buy produce via an honesty box.

At first Martin enjoyed a drink, had flings with a number of women, and was visited by carousing mates from cane farms around Mackay, where he'd worked briefly before coming to the island. Gradually, though, the fun began to drain out of Lord Percy, as the yachties called him. He became preoccupied with religion, and was increasingly short-tempered and unpredictable.

By 1985, when Radclyffe came from England for her first visit, he was far from the "gallivanting ladies' man" of family legend. "There was some peculiarity to his character," she says, "that later was [diagnosed as] a mental illness ... but I don't know when or how he became interested in Biblical prophecy."

John Morris (Radclyffe's partner of seven years) weighs into the conversation for the first time. "I understand Andy's father was an army general," he offers, grinning, "and that they called him 'Mad Martin'. So it probably ran in the family."

Radclyffe quickly changes the subject. (Weeks later, when I call her to clarify a few points, she says she also accepts the truth of biblical prophecy, including the concept of "end times" - a period seen as heralding the second coming of Christ and the ensuing apocalypse: "But everybody seems to have a different opinion of how it's actually going to work.")

Religious fundamentalism and isolated, self-sufficient communities often go hand-in-hand, and Martin increasingly saw Middle Percy as a lifeboat in a world "drowning in sin". But how did an educated, carefree adventurer come to embrace such grim notions? Jon Hickling - who, with his wife, Liz, and their two young sons, lived on Middle Percy for 12 years - solves that abiding mystery with two words: egg cartons.

"The story Andy told us," he explains, "was that sometime in the late '60s, the Whites [former leaseholders] sent him over some egg cartons he needed on the stores boat. They were wrapped in a magazine from the Worldwide Church of God, led by someone called [Garner Ted] Armstrong. Andy wasn't religious up to that point, although he grew up in the Church of England, but when he unwrapped that magazine, and read it from cover to cover, he just went, 'Wow!' He felt like he'd been hit on the head by a thunderbolt and had seen the light."

Martin subscribed to the magazine, and became a convert to the church's theory, known as British Israelism, which holds that white races (especially the British) are descended from the Ten Lost Tribes of Israel, and are God's "chosen people". Before falling from favour for his philandering, Armstrong - described by one US writer as preaching to a "subculture of lonely, frightened, disoriented Americans" - also had a worldwide radio audience of millions, including Andy Martin.

By the early '90s, with his physical health in decline, Martin had become unbalanced. "He believed he was being communicated with directly by God as some sort of prophet," Hickling tells me. "It was very interesting, to say the least."

The Hicklings were practical yachties who'd arrived on Middle Percy in 1989. They built their own house near the homestead - "We couldn't have lived with Andy; others tried and just couldn't cope" - worked long hours improving the island's gardens and infrastructure, taught their sons via distance education, and did their best to look after the evermore erratic Martin.

In 1996, Martin left the island, telling the Hicklings he had to return to England to warn the British people of God's coming retribution unless they changed their evil ways. He promised to contact Queensland's Department of Natural Resources (now Environment and Resource Management) and have the Hicklings named joint leaseholders in recognition of the effort and money they'd put into Middle Percy. But because the latest 10-year pastoral lease was soon to expire, the department declined - a fateful glitch the Hicklings weren't aware of until it was too late.

For the next few years, Martin stayed at the home of a friend called Rebecca Comyn in the Gloucestershire village of Ebrington. Cathryn Radclyffe, by this stage, had become a permanent resident of Australia and lived at Proserpine, near Mackay.

In the homestead on Middle Percy, she tells me how, on September 30, 2000, Martin got his friend, Comyn to drive him to Princess Diana's family home, Althorp House, in Northampton-shire, where her body is buried on an island in an ornamental lake known as The Round Oval. "This was the time of a [British-Israelite] feast day known as the Feast of the Trumpets, and that's when Andy had figured out that Lady Diana would arise from the dead, and that [his presence] would be integral as part of that."

John Morris: "It was sort of his interpretation of prophecy."

Radclyffe: "Andy thought Diana and her sons would then come back with him to this island ... there are various references in the prophecies to islands, and, you know, he always called this place Little England, and you can see it all going through his head ..."

She trails off, staring at a picture on the table of bearded Andy Martin in his prime, seated in the stern of a boat off Middle Percy.

"He was drawing a long bow," offers Morris.

"Anyway," Radclyffe continues wearily, "when Lady Di didn't rise from the dead, that would have devastated him. Because it was the [conclusion] of everything he'd been writing about. His whole life ... well, at that point that was the only thing left. The island was the first thing in his life, and that became the second. He'd already written that if he was wrong [about Princess Diana], he'd be a false prophet. And that false prophets get, you know, killed by God, or wiped out somehow."

Strangely enough, it was in December 2000 - while Martin was awaiting punishment at the hands of God - that the Hicklings first encountered a man called Mick Cotter. They were in Cairns restoring an historic boat called The Islander, built on Middle Percy by the White family, when Cotter came to the boatyard and introduced himself. Then 33 and sporting a mohawk, Cotter was a giant of a man, festooned with tattoos, including - on his back - two sets of skull-and-crossbones which, he told the Hicklings, were done with ink that glowed in the dark.

Cotter had visited Middle Percy in the early 1980s on his parents' yacht, then spent a few months living there with Martin. According to Radclyffe, Cotter's parents told Martin they were at their wits' end with their wayward son, and Martin - who had ideas of assisting homeless or problem kids on the island - agreed to help.

When the Hicklings returned to Middle Percy from Cairns in 2000, towing the repaired Islander, Cotter - who told them he'd like to revisit the place - came along as part of the crew. "Little did [we] realise," the Hicklings later wrote, "how this strange encounter was going to turn [our] island dream into a nightmare!"

After a short stay, Cotter left the island laden with gifts. Because he'd claimed he wanted to write to his "old friend", the Hicklings had also given him Martin's address in England.

Soon after returning to Cairns, Cotter flew to London, went to the village where Martin was staying with Comyn, and - according to court evidence given later by Comyn - put sustained pressure on Martin to sell him the Middle Percy lease. Comyn said Cotter denigrated the Hicklings to Martin, claiming they'd let the island deteriorate, and that the lease was at risk of being revoked by the government. She said Cotter told the agitated Martin that if he sold the lease, Cotter would take Martin back to live on the island and "accommodate his disabilities".

The upshot was that Martin flew back to Australia with Cotter, and, within four days of them arriving in Cairns, had signed the island lease (then valued at $320,000) over to Cotter for just $10.

Soon afterwards, "stunned and sickened" by what had happened, the Hicklings left their island home of 12 years on their converted pearling lugger, Ruby Charlotte, and Cotter and his friends moved in. The "black period", as visiting yachties called it, had begun.

On the homestead veranda, Radclyffe tells me Cotter had been aware, through his contact with the Hicklings, of Martin's mental frailty. "Andy was ripe for the plucking," she says bitterly.

After signing over the island to Cotter, Martin stayed for a time with Radclyffe in Proserpine. When she asked why he'd broken his promise to the Hicklings, who loved the island as much as him, Martin flew into a rage: "I thought he was going to have a heart attack! But of course, as we discovered later, he'd been poisoned against the Hicklings by Cotter."

Apart from the $10 paid to make the contract between them legal, the District Court of Queensland would later hear that Cotter had undertaken to pay Martin $150,000 for his lease, but never did. Early in 2002, still believing Cotter was a "rich businessman" who would pay him the amount owed, Martin returned to England, where he lived alone for several months in a bed-and-breakfast.

"He was in a terrible state," says John Morris. "He would wake up at night from screaming nightmares, kicking and bashing the walls, and ranting up and down the hallways."

Radclyffe closes her eyes. "Poor Andy," she says. She didn't know of Martin's ordeals until Rebecca Comyn rang to say he was desperate to return to Australia: "I met him at Proserpine Airport, and he was just a wreck. I took him back to my place and for the first time ever, he said he wanted to see a doctor. When he did, the next day, the doctor immediately had him admitted to hospital." Back at her place a few days later, Martin began regaling her with his concerns about Middle Percy. "He'd say things like, 'I was going to lose the island! ... The Hicklings weren't looking after it, but Cotter said he would! ... Don't worry about the $10, it's just for tax purposes!' "

After further medical treatment, Martin hired a solicitor and began a civil action to try to regain control of the island lease from Cotter. As the long process dragged on, he gave Radclyffe power of attorney over his affairs, and made a will leaving the lease to her should the court decide in his favour. In late 2002, Martin was examined by a psychiatrist who found he was suffering from a form of schizophrenia characterised by paranoid delusions, and dementia.

Mick Cotter's reign on Middle Percy lasted seven years. During that time, according to the Hicklings, Radclyffe, Morris and others, the infrastructure was neglected, the gardens perished and the goats, ponies and cattle all died. Produce was no longer available at the A-frame in West Bay, signs appeared warning visitors not to venture beyond the beach, and yachties who'd been calling there for years began giving it a miss.

"Some of them told me they'd sail into the bay and get a horrible, ominous feeling," says John Morris. "There was a blackness about the island that no one had experienced before."

Cotter, often off the island, left "caretakers" in charge, but Hickling says they were barely able to care for themselves, and had to scrounge food from visiting boats.

Morris: "When he was here, Cotter would invite a lot of his bikie mates from the mainland over for big parties down at the A-frame."

Andy Martin made his last visit to Middle Percy in August 2002, flying in by helicopter with a supply of medication for his ailments. Cotter wasn't on the island. "The place was a wreck," says Radclyffe. "No food, no water, animals dead and dying." Martin sat on the homestead veranda for five days surveying the wreckage and reading his Bible, then left.

He died the following year at a nursing home in Mackay, aged 76. "I visited him that same day," Radclyffe tells me. "He was sitting up in bed and I supported his back so that he could eat his lunch. Then I had to go home to lock up my chickens. I'd just got home, then - phone call - Andy was dead. I'd just been talking to him!"

In late 2004, Cotter issued a long, rambling statement to The Coastal Passage, a popular paper and online forum for boaties, denying he'd tricked Martin out of his lease. Instead, he insisted, he'd heard of Martin's infirmities and decided to "jump on my white steed and gallop off to my old friend's rescue ... [Martin] said he couldn't sell me the lease, but would gladly give it to me knowing I would only do what was right for the island."

To those critical of his stewardship of Middle Percy, Cotter responded: "Andy ... gave [the island] to me. It is my home now, nobody else's ... we do not have to supply bread, fruit, vegies or anything to anyone ... everybody thinks they own some part of this island. In fact they do not. I do. I own all of it."

In 2005, Radclyffe - who'd been "praying very hard" for someone to help her with the continuing legal wrangle over the island - met the down-to-earth John Morris at a music festival near Mackay. They were married soon afterwards - "Not officially," notes Radclyffe, "we just took on marriage agreements in the biblical sense."

Finally, on June 19, 2008 (almost three years after proceedings began), District Court Judge Bob Pack found that Mick Cotter had exploited Andy Martin by exerting undue influence. He found that Cotter had "coaxed" Martin back from England to sign the lease at a time when Martin's "love of the island, his physical and mental frailty made him vulnerable", and that this constituted unconscionable exploitation. Judge Pack ordered that the lease be transferred to "Mrs Morris" (Radclyffe), and that Cotter leave the island by the end of the following month.

In a recent addendum to his book, The History of the Percy Isles, Jon Hickling wrote that after the court ruling, "anything that was too [difficult to remove] by the departing leaseholder was destroyed, burnt, or 'spiked' to make it inoperable. He even took the honey out of the remaining beehives ..."

John Morris was standing on the shore when Cotter finally left the island: "He wasn't a happy lad. He turned and yelled out to me, 'Next time we meet you better pray you're not alone, you c...!' "

Mick Cotter is now thought to be living in Asia. Good Weekend sought details of his whereabouts, so that he might comment, but wasn't successful. Radclyffe and Morris have spent four years restoring the island's gardens and infrastructure, and its time-honoured hospitality to mariners. But with Queensland's new Liberal National Party government reviewing the status of various national parks in the state, Middle Percy's future is uncertain.

As we sail out of West Bay, bearing fresh fruit and honey, I stand on deck watching the island diminish in our wake. Clouds rush in, darkening its peaks, then pass, restoring them suddenly to the light. "Are you weary of the journey," asked poor old Andy Martin on one of his trackside signs, "Does your burden seem too great? ... Courage! This may be the spot / Where joys return and troubles end."