Nutt and the Taunton-based psychiatrist Dr Ben Sessa are two of the British scientists who hope to repeat an experiment on patients with post-traumatic stress disorder (PTSD) undertaken in the US which, although small, was successful and has caused some in the scientific community to think what was until recently unthinkable. It involved 20 people who had been in therapy and on pills for an average of 19 years. Twelve were given MDMA – or 3,4-methylenedioxymethamphetamine, the chemical compound found, often adulterated, in ecstasy tablets. The rest had placebo pills but were later also given the chance to take MDMA. Each one had a therapy session, lying back in a reclining chair in a pleasant flower-decorated room in South Carolina, wearing an eyemask.

Sometimes they listened to music on headphones and sometimes they talked to the therapist, all the while thinking about the events that had caused such profound distress that they had been unable to revisit it in past psychotherapy sessions.

The response rate was a remarkable 83% – 10 out of the 12 showed significant improvement two months after the second of two MDMA therapy sessions. That compared with 25% of those on the placebo. There were no serious side-effects and no long-term problems.