A new book casts fresh light on an undercover operation that smashed one of the most extraordinary drug rings the world has ever seen and changed British policing forever. What was Operation Julie?

It was hardly a typical drugs bust. When police from around the country swooped before dawn one morning in 1977, dozens of the 800 officers working the case looked like unshaven, long-haired hippies plucked from the audience of a Pink Floyd gig.

And the vast LSD co-operative they were targeting was, if anything, even more unconventional.

Its leading members included doctors, scientists and university graduates - motivated, they insisted, by an evangelical drive to transform human consciousness itself.

But for all their peace-and-love ideals, their conspiracy was, at the time, the biggest drug ring the UK had ever seen and one of the world's largest. After officers seized a haul large enough for six million trips, the price of an acid tab on Britain's streets reportedly leapt from £1 to £5 overnight.

The investigation, codenamed Operation Julie, didn't just destroy one cartel.

LSD Invented in 1938 by Swiss scientist Albert Hofmann while he was researching the medicinal uses of a crop fungus

Began to gain popularity as a street drug in the mid-1960s but banned in the UK in 1966

The maximum penalty for possession is seven years in prison and life for supply

Commonly causes visual and auditory distortion, with "trips" lasting up to eight hours Did LSD change Britain?

It arguably represented the final death throes of the 1960s counterculture, conclusively shattering the idealism with which many had once viewed the drugs scene and marking the start of a harsher, more brutal era for the narcotics underworld.

In addition, its unprecedented scale and co-operation between forces changed forever the way Britain was policed and set the tone for the so-called war on drugs of the 1980s.

The inquiry led to raids on 87 homes, resulting in more than 100 arrests and 15 ringleaders being sentenced to a combined 120 years in jail.

But it began in the unlikely setting of Cambridge University's radical academic fringe, inspired by LSD pioneer Timothy Leary's belief that the drug broadened the mind and could transform society for the better.

The catalyst was David Solomon, a Californian bohemian intellectual and associate of Leary's who came to Cambridge in 1967. Two years later he was introduced to Richard Kemp, a Liverpool University chemist. Soon Kemp was meeting others in Solomon's circle and their first LSD production runs began at the American's home, a former vicarage.

I was convinced that this was the answer to the world's problems Leaf Fielding

One of the radicals who came to assume a key role within the organisation was Leaf Fielding, an anarchist former public schoolboy who had dropped out of university following his introduction to acid at the age of 18. He began as the tabletter, turning the raw chemicals into individual doses, and later took over the distribution network.

As he recounts in his newly released memoir, To Live Outside the Law, the fullest account yet of the Operation Julie story by a conspiracy insider, it was the promise of building a new society and seeking a way out of the cold war's nuclear stand-off that drove the gang at first rather than money.

"We were all extremely idealistic," he recalls. "I was convinced that this was the answer to the world's problems.

"We saw it as a new awakening out of the terrible impasse that the world had got itself into."

In 1973, fearful of police attention, one wing of the co-operative led by Kemp and Solomon moved to west Wales while another branch remained in London.

Image caption Houses in west Wales were among those raided by Operation Julie officers

The influx of these counter-cultural figures into villages and towns like Llanddewi Brefi - later the fictional home of Little Britain's Dafydd - and Tregaron was less conspicuous than might be imagined.

Ceredigion's natural beauty and low cost of living had already attracted a sizeable hippy population, according to Lyn Ebenezer, author of Operation Julie: The World's Greatest LSD Bust, who was working as a local freelance journalist at the time. The likes of the Rolling Stones, John Lennon and Jimi Hendrix had all made pilgrimages to the area.

The LSD ringleaders all held down jobs, mixed with their neighbours and stood their rounds in local pubs. As a result, Ebenezer says, they quickly became popular figures.

"They were great characters," he says. "They added colour.

We were totally convinced that we were doing the right thing Dai Rees, Operation Julie surveillance officer

"Yes, they were differently attired to the locals. But most country dwellers knew they weren't the archetypal hippies who don't do any work and just pick up their Giros [benefit payments]. They were part of the community."

Indeed, like many in the ring, Fielding did not need to take the risks he did. By the time of the raids, he had built up a thriving legitimate business, a healthfood shop, in Reading. Shortly before the bust he told his co-conspirators that he wanted out.

"We began as idealists but then paranoia crept in," he recalls.

They had good reason to be paranoid. After police discovered a torn-up piece of paper spelling one of the ingredients of LSD in Kemp's car following a crash, an unprecedented multi-police force drugs investigation began. It was codenamed Operation Julie after one of its officers, Sgt Julie Taylor, and later name-checked in the Clash song Julie's Been Working for the Drug Squad.

Listening devices were installed in the ringleaders' home and dozens of undercover officers were sent into west Wales posing as hippies to place them under surveillance during a 13-month operation.

Dai Rees, then a drugs squad inspector with Dyfed Powys police, was one of those who transformed themselves.

"We grew long hair, we wore jeans, we looked quite scruffy," he remembers. "To have worn a stiff collar and tie would have been impossible."

On 26 March 1977, detectives finally swooped. They uncovered evidence of a massive operation, exporting to 100 countries and, according to some reports, supplying 90% of the UK's LSD.

Share certificates and details of Swiss bank accounts provided further evidence that the ring had come a long way from its early, idealistic roots - it was now a multi-million pound, multi-national corporation.

The gang jailed in the Operation Julie raids had their money seized, but the Law Lords ruled that this should not have been taken

So the authorities demanded that the ring each pay tax on their LSD earnings

The gang were offered a deal so that all funds taken by the police would be accepted as tax on their profits

Leaf Fielding's tax assessment (above) blandly itemised his earnings as a "drug salesman"

For the police, halting the gang and jailing its leaders was viewed as a massive achievement and subsequent investigations would follow the cross-force example of Operation Julie.

Dai Rees remains proud to have played a role in this collective effort.

"We were totally convinced that we were doing the right thing," he says. "I think every police force in the country at that time had some experience of individuals who had ended up in mental hospitals or been involved in serious crime as a result of of LSD."

But, nonetheless, he couldn't help seeing the incarceration of such intelligent and a well-educated people as a tragic waste.

"When you see such talent going down the stairs from the dock to start a term of imprisonment, you don't leap around with joy," Rees says.

Kemp was sentenced to 13 years in prison and his partner Christine Bott, a qualified doctor, to nine years. Their convictions led to the end of the ring's LSD-manufacturing activities.

Fielding, who was sentenced to eight years in prison, observes that the drugs gangs who stepped into the vacuum were far nastier than his own.

Having built up another food business and opened an orphanage in Malawi following his release, he says he has no regrets. Nonetheless, he no longer believes in the capacity of LSD to transform the planet.

"I now realise how unrealistic that was - you can't solve the world's problems with a pill," he acknowledges.

"Obviously some people did suffer and I don't feel great about that. But some drugs work for some people and others don't - I like a drink with my meal but I'm not an alcoholic."

Views about the war on drugs, in which Operation Julie can be seen as the opening campaign, will remain divided. But the legacy of a group of hippies in rural Wales lives on.