At the crumbling colonial farm buildings in Porto Real, agricultural worker Kimilson Lima, 43, has signed the agreement and he’s happy. “With this money we can have a proper floor in the house,” he said. “And an inside toilet.”

Lima is part of a ground-breaking experiment on the West African island of Príncipe, where villagers who agree to follow an environmental protection code will reap a quarterly dividend. To date nearly 3,000 have joined the Faya Foundation’s project, more than 60% of the adult population. The first payment of €816 (£708) has just been delivered, a large amount of money on the island. “This will be truly transformative, both for nature and for the people,” said the president of the self-governing region, Felipe Nascimento.

The special nature of Príncipe’s flora and fauna has been known since the 20-mile-long island was stumbled upon by Portuguese navigators in 1471. Uninhabited and separated from the African mainland by over 160 miles of ocean, both Príncipe and its larger southern neighbour, São Tomé, had evolved unique rainforests where giant land snails and crabs were among the top predators. Even now, new species are still being discovered, leading to the nickname “African Galapagos”.

The Portuguese started a cacao plantation economy, but after independence in 1975, that business fell apart. On Príncipe, the descendants of slaves and labourers from Angola and Cabo Verde became tight-knit communities of subsistence farmers, camping out in the increasingly decrepit colonial-era buildings. For the occasional visitor, it was picturesque, but problems were mounting for residents who were being pushed deeper into unexplored parts of the island, cutting trees and foraging.

Then, in 2010, South African billionaire Mark Shuttleworth arrived, looking for somewhere to build a house, an idea that was soon replaced by a philanthropic urge to help. One former plantation house was converted into a hotel with locals retrained as staff, but Shuttleworth did not stop there. His quest was to fund the type of sustainable development that also protected and improved the environment. “The normal path to development for Príncipe would be to cut down forest and grow ‘fair trade’ peppercorns,” Shuttleworth said. “But we want to reward them as stewards of their precious environment.”

That dream has now reached fruition, much to the surprise of local sceptics. “They’ve been let down in the past,” says Faya project CEO, Jorge Alcobia. “They didn’t expect us to keep our promises.”

There is still, however, a learning process about how to help the environment. “We have to explain that it’s not free money,” said Alcobia, “Dividends are reduced, for example, if there’s unauthorised tree-felling.” Faya is funding school improvements, organising the moribund cacao business, and giving financial advice. “A lot of people here have no bank account and little experience of handling money.”

So far, however, all the money comes from Shuttleworth’s fortune, a past and future commitment that totals about £87m. Among the developments is a new village, home to Clara Gomes and her daughter. “My money is going on a new kitchen and training in carpentry,” she said.

Her neighbour, Edmundo, is selling cacao to the project. “I had no one to buy it before,” he said. “I’m hoping they might take vanilla next.” He has signed up for the dividend, but others remain sceptical. “It’s a monopoly,” shouted a bystander, “Is that good? And what if everyone buys motorbikes and chainsaws?”

For one man, years spent foraging in the forest have now blossomed into a career as wildlife guide. Yodiney dos Santos now leads scientific expeditions into the forest, discovering several new species, including a previously unknown owl. He knows only too well how fragile this environment is. “My ancestors came here from Angola,” he said. “And, for food, they brought the edible West African snail, which then escaped. Now those snails are pushing out the endemic Príncipe snails.”

This unique social experiment will be watched closely. “If it’s successful,” said Shuttleworth, “I hope other irreplaceable ecosystems might benefit from the idea at scale.”