Rainbow-coloured fish swirled around my legs in crystal-clear South Pacific waters. On a semi-tropical rainforest walk, I clapped my hands and chirping flightless birds ran towards me, tame from lack of predators. People rode bicycles along 13km of narrow roads, through shady tunnels of overhanging palms and kids strolling to school barefoot. There were no billboards, room keys, bike locks or mobile phone reception.

Dropping coins into honour boxes, I picked up an avocado at a roadside fruit stand, a mask and snorkel at a deserted beach shack and a cart and clubs at the nine-hole golf course. Rarely were there more than two other people sunning themselves on one of the island’s 11 white-sand beaches, and the biggest crowds I saw were at the weekly fish fry.

Lord Howe Island is just 11km long and 2km wide, an idyllic boomerang-shaped sliver of land 780km north-east of Sydney. The island hugs a turquoise lagoon rimmed with the world’s southernmost coral reef and was designated a Unesco World Heritage site in 1982 for its spectacular volcanic geography, rare endemic fauna and native plant species found nowhere else on Earth. After a 1997 visit, British natural historian Sir David Attenborough described it as, “…so extraordinary it is almost unbelievable... few islands, surely, can be so accessible, so remarkable, yet so unspoilt.”

Yet this piece of paradise is notoriously too pricey for most travellers to experience. Though just a two-hour flight from Sydney or Brisbane, it’s actually cheaper to buy a ticket to Los Angeles. Restaurants are expensive, as are the island’s upscale lodgings, which might be booked solid a year in advance. There is no camping or budget accommodation and cruise ships are banned.

You may also be interested in:

• Australia's bizarre coastal desert

• Is this Greece's last island paradise?

• The Australian island discovered by accident

Is Lord Howe Australia’s most exclusive island then a retreat for the super-rich that looks down its nose at the everyday traveller?

Not at all. In fact, it’s exactly the opposite.

Everything about Lord Howe is laidback, except for the fervour with which its locals protect their paradise. The uninhabited island was only discovered in 1788 and many residents are descendants of the first European settlers in 1833. For them, a pristine environment has been their bread and butter for almost a century since tourists first landed on the lagoon in Sandringham Flying Boats in the late 1940s.

In 1981, long before “eco-tourism” was a buzzword and “overtourism” a curse, the 350 or so permanent locals expressed concerns about habitat destruction, invasive species, pollution and development. As a result, the elected Lord Howe Island Board, comprised of four locals and three members of the New South Wales state government, capped visitor numbers to a maximum of 400 at one time. And so it remains.

The island has strict rules and environmental policies. Cars are limited to residents who need them. There is no air conditioning. The Board must be consulted before a tree branch is felled or a house paint is chosen. “We joke that you need a permit to dig over your garden!” said long-time resident and guide, Clive Wilson. "We're accused of being bureaucracy gone mad, but our goal is to preserve our unique and delicate environment."

Our goal is to preserve our unique and delicate environment

Libby Grant, manager of Capella Lodge, filled me in on island life on the short shuttle from the airport to the nine-suite resort in an electric golf cart. Like all residents, the lodge gathers rainwater for drinking, and uses bore water for washing and gardening. “One of our biggest challenges can be waiting for the fortnightly barge to arrive with food and supplies from the mainland,” she said. Luckily, island nurseries grow fruit and vegetables. “Our chef also forages for sea vegetables from around the island’s foreshores and fishermen supply us with freshly caught kingfish.”

Recycling is a major part of daily life. Organic waste from homes, restaurants and public bins plus sewage sludge, paper and shredded cardboard go into a vertical composting unit, a world-class facility that converts 86% of the island’s rubbish into compost for the community. Recyclable plastics, aluminium and glass are shipped ashore and sold to offset freight costs. Non-recyclables are compacted and end up at a mainland dump as there is no longer one on the island. A user-pays system discourages household junk disposal, which means that to buy a new sofa it might cost $1,200 to ship the old one out.

Electricity also carries a big bill – a long-awaited solar and battery system to reduce expensive and polluting diesel dependence is scheduled for completion in 2020.

“The high costs for locals and businesses are a result of remote island life becoming more contemporary and environmentally friendly,” said Grant, especially when accommodating a clientele expecting all the comforts of home within the range of Lord Howe’s strict eco-limits.

I grabbed a free bike from the rack and cycled into the island’s tiny township half hidden in tropical foliage. There’s a community centre/theatre, a bakery, butcher and general store; a post office, a couple of funky shops and Government House where the birth of a new island baby is announced by a pink or blue “nappy” run up the flagpole. Profits from sales at the bottle shop, which is operated by the Island Board, are funnelled back into local improvement projects, which means “cracking a tinnie” (a colloquial Australian expression for “opening a beer”) is literally a community service.

The tiny island landscape is diverse, from dense rainforest and steep mountains, so there are a dozen or more outdoor activities to enjoy, including surfing, mountain biking and lawn bowling. At the 6km-long lagoon, I rented a kayak and paddled out to Rabbit Island, which I had to myself for a picnic lunch.

Back ashore, I slipped into scuba gear on a dive boat and communed with swarms of tropical species from warm Great Barrier Reef currents that mingle with Lord Howe’s cooler waters. This mixture creates a rich and unusual collection of critters and corals not normally found rubbing shoulders, like temperate tuna and salmon alongside tropical angelfish and 86 types of hard coral.

In late afternoon, I pedalled to Ned’s Beach for the ritual of feeding fish in the shallows.

The following morning, I joined a small group for a humid, full-day hike up 875m Mount Gower looming up from the island’s southern tip alongside its tropical twin, Mount Lidgbird. Our guide, Jack Shick, is a fifth-generation islander and third-generation mountain guide. “About 170 species of sea and land birds live on or visit the island where they don’t have any predators,” he said about this birdwatcher’s paradise. “Now I want you all to yodel loudly.” We did, and Providence petrels swirling overhead suddenly dropped to the ground with curiosity, clumsily waddling towards us with long outstretched wings.

The hike became ever more surreal as we approached the misty, mossy cloud forest summit, a Tolkein-esque world of stunted and gnarled trees, orchids and dripping ferns.

But as much as I was enchanted by Lord Howe’s natural attractions, what was even more rewarding was experiencing the passion and determination of a tight-knit community focussed on protecting their fairy-tale island.

We have grown up with a foundational belief that it is our responsibility to protect our environment and way of life

At the Lord Howe Island Board office, I met member and sixth-generation islander Darcelle Matassoni, who left for a mainland education and career in 1998. “After my daughter was born in 2014, I realised it would be remiss not to allow her to grow up in this environment,” she told me, explaining that she moved back the following year, taking seven part-time jobs to survive. “I love that we think ‘devices’ on this island are masks, snorkels and bikes; that we swap vegetables and fruit for eggs or fish; and live ‘in season’,” she said. “And that we have grown up with a foundational belief that it is our responsibility to protect our environment and way of life.”

Just down the road at the intriguing Lord Howe Island Museum covering local heritage, history, shipwrecks and nature, I sought out curator Ian Hutton, resident naturalist and author of 10 books on the island, including A Guide to World Heritage – Lord Howe Island. “People talk about the Galápagos Islands because of Darwin's connection, but there's more diversity on Lord Howe Island and it's so intact – the island is very much as it was when it was first discovered,” said Hutton, an islander since 1980. “And we are all working to return this island to its original state as much as we can.”

Feral cats, goats, pigs, and, in 2019, rats have been eradicated – all having decimated endemic flora and fauna. Native animals have been brought back from the brink of extinction, like the flightless Lord Howe woodhen (roughly 30 remained) and one of the world’s rarest insects, the Lord Howe Island Phasmid.

Lord Howe also leads the world in the eradication of noxious weeds, reducing infestations by 90% in one of the most ambitious weed-eradication projects on an inhabited island.

Since 2001 Hutton’s zeal has been channelled into his Friends of Lord Howe Island project, working with volunteers who pay to visit the island and spend half of each day removing weeds or regenerating bushland. “It’s a more economical way to visit, plus they feel they’re contributing to the island’s future,” he said. “We’ve logged 26,622 hours of volunteer time and some people have returned a dozen times or more.”

Locals and visitors can also work together as citizen scientists alongside conservationists with LHI Conservation Volunteers to protect the island’s biodiversity from its mountaintops to the bottom of the 460-sq-km Lord Howe Island Marine Park, which was established in 1999. “We protect Lord Howe from the impact of tourism that some other destinations experience by offering conservation programmes in which both residents and visitors can take part,” said Lord Howe Island’s executive officer of tourism, Trina Shepherd.

In 2018, for its long history of sustainable and conservation programmes, the Lord Howe Island Board received Australia’s top eco award, the Gold Banksia.

Then, in autumn 2019, the international tourism spotlight focused for the first time on the remote island when Lonely Planet placed it in their Top Ten Regions to visit in 2020. How will that affect this fragile environment, I wondered?

“Though we are proud of Lonely Planet’s designation,” said Shepherd, “we don’t expect any change or significant impact, as our visitor numbers were long ago capped.” Bookings, however, may have to be made further in advance due to the worldwide exposure. “We are certainly receiving more requests,” she said.

This was my third visit to Lord Howe Island since 1983, and by the time it came to an end I was thrilled to confirm a remarkable fact that is sadly rare these days: that my favourite place on Earth has remained charmingly retro, uncrowded, undeveloped, just as strongly community-oriented and even more environmentally pristine than it was 36 years ago.

It can be done.

Islands of Imagination is a BBC Travel series that journeys to some of the world’s most unique, extreme and beautiful places that have been inimitably fashioned by their geographic isolation.

Join more than three million BBC Travel fans by liking us on Facebook, or follow us on Twitter and Instagram.

If you liked this story, sign up for the weekly bbc.com features newsletter called "The Essential List". A handpicked selection of stories from BBC Future, Culture, Worklife and Travel, delivered to your inbox every Friday.