On 16 August 1951, postman Leon Armunier was doing his rounds in the southern French town of Pont-Saint-Esprit when he was suddenly overwhelmed by nausea and wild hallucinations.

“It was terrible. I had the sensation of shrinking and shrinking, and the fire and the serpents coiling around my arms,” he remembers.

Leon, now 87, fell off his bike and was taken to the hospital in Avignon.

He was put in a straitjacket but he shared a room with three teenagers who had been chained to their beds to keep them under control.

“Some of my friends tried to get out of the window. They were thrashing wildly… screaming, and the sound of the metal beds and the jumping up and down… the noise was terrible.

"I’d prefer to die rather than go through that again.”

Over the coming days, dozens of other people in the town fell prey to similar symptoms.

Doctors at the time concluded that bread at one of the town’s bakeries had become contaminated by ergot, a poisonous fungus that occurs naturally on rye.

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Albarelli believes the Pont-Saint-Esprit and F. Olson Files, mentioned in the document, would show – if they had not been “buried” – that the CIA was experimenting on the townspeople, by dosing them with LSD.

The conclusion drawn at the time was that one of the town’s bakeries, the Roch Briand, was the source of the poisoning. It’s possible, Albarelli says, that LSD was put in the bread.

It is well known that biological warfare scientists around the world, including some in Britain, were experimenting with LSD in the early 1950s – a time of conflict in Korea and an escalation of Cold War tensions.

Albarelli says he has found a top secret report issued in 1949 by the research director of the Edgewood Arsenal, where many US government LSD experiments were carried out, which states that the army should do everything possible to launch “field experiments” using the drug.

Using Freedom of Information legislation, he also got hold of another CIA report from 1954.

In it an agent reported his conversation with a representative of the Sandoz Chemical company in Switzerland.

Sandoz’s base, which is just a few hundred kilometres from Pont-Saint-Esprit, was the only place where LSD was being produced at that time.

The agent reports that after several drinks, the Sandoz representative abruptly stated: “The Pont-Saint-Esprit ‘secret’ is that it was not the bread at all… It was not grain ergot.”