IT stands as the only remaining memorial to a scheme that just a century ago would, it was claimed, turn the Quantock coast into the country’s oil capital with a production of five million gallons a year and bring unprecedented wealth to West Somerset.

Today, visitors passing on their way to Kilve beach see only a brick box with a rusty chimney on its top. That’s if they notice it at all.

Appearances are deceptive. Now protected by listed building status, the Kilve Pill oil retort house is all that remains of a massive scandal which rocked the financial world of the 1920s and sent to jail a fraudster who described himself as “the greatest living expert in the petroleum world.”

A judge preferred the description: “A highly dangerous and plausible criminal.”

When the scheme was hatched in 1922, speculators were asked for capital of £1.5 million (£68 million in today’s currency) and were told they would double their money in months. In fact they lost every penny they invested.

The key to the scam lay in the oil shale in the lias rocks deep under the cliffs at Kilve, centre of what was claimed to be a rich oil-bearing outcrop stretching from Watchet to the River Parrett.

Seven years earlier, an engineer named John Berry had sunk an exploratory bore-hole at Kilve and discovered oil-bearing shale at a depth of 91 metres and which was thought to cover an area of 8,000 acres, extending nearly two miles inland.

Kilve shale had long been known to have special qualities - it could be set alight by beach bonfires - but financial and technical problems meant that the cliffs lay undisturbed until 1920 and the arrival in Kilve of small grey-haired man with a precise Aberdeen accent.

He was Dr William Forbes-Leslie, who lost no time in declaring that Kilve had the potential to “bring untold prosperity to the area and transform the lives of everyone fortunate enough to become involved in this truly inspiring project.”

With that end in mind, Dr Forbes- Leslie launched Shaline Ltd, a company looking for capital of £1.5 million and chaired by the Duke of Athol and supported by backers including an ex-mayor of Bridgwater.

The plan was to extract and process the shale oil at Kilve and transport it on a new 11-mile railway costing £200,000 to a fuel terminal at Bridgwater docks.

Journalists from local and national newspapers, including the Free Press, were taken on tours of the beaches under which untold riches were claimed to lie.

They learned that mining operations would be centred on Kilve Pill, a creek and landing-point which had been used since the Middle Ages to bring in fuel for lime kilns, and that plans for the railway were already being considered by the Ministry of Transport.

The “West Somerset oil boom” became hot news. In a Free Press interview, Dr Forbes-Leslie revealed what was described as “much interesting material”, claiming that the layers of shale ran inland “for a considerable distance in outcrops from 200 to 300ft high.”

As a bonus, the shale would also yield a residue resembling black sealing-wax which could be used as “a wonderfully fine varnish” and ash from the process could be mixed with limestone to produce “an inexhaustible amount of cement.”

Dr Forbes-Leslie declared that Kilve shale was “of a thickness so great and giving an oil content so rich as to astonish scientific investigators.” He estimated that at least nine billion tons of shale and three billion tons of limestone were there for the taking.

“With the right technology, the hills can be blasted down, and rich oil fuel picked up by steam shovel and loaded on to railway trucks for three shillings (15p) a ton.”

Not surprisingly, hopes were high. But soon rumours began to circulate that there were problems. The Free Press reported that “only a small trickle of oil” had emerged from the retort and was found to be contaminated by sulphur. The lower shale seams, which might have been more productive, were found to be not cost-effective to mine.

Dr Forbes-Leslie brushed aside such problems as “minor setbacks”, but by now questions were being asked, and the truth, when it finally emerged in 1923, would reveal a fraudulent scheme on an epic scale.

The doctor was no oil expert, but a maverick GP and serial bankrupt, author of adventure stories in “Boys’ Own Paper” and a conman masquerading under the fake title Duc de Villanda.

It seemed he developed an interest in mining while researching in South Africa for a paper on malaria which appeared in the Lancet. Only months later, he was a member of the Geological Society and was fast establishing a reputation as a leading authority on shales.

It would be ten years before the law finally caught up and William Forbes-Leslie was found guilty with two other men of what was described as an “impudent £400,000 fraud” and jailed for two years. He was subsequently struck off the medical register and died aged 70 in 1944.

The Kilve site was abandoned, the link railway never built and the Quantock Hills left in peace.

Today, only the retort house remains, foliage growing from the chimney in the shape of a plume of smoke, to provide a reminder of what might have been.