“Three years ago if I was asked the question would psilocybin [the psychedelic compound in magic mushrooms] work for veterans, I would have said it would be quite dangerous to relive the trauma when tripping. But so many vets are doing it now that I’m convinced it can work.”

It is estimated that 17% of people who have seen active military service report symptoms such as flashbacks, nightmares, anxiety, depression, grief and anger.

Earlier this year a team at the Medical University of South Carolina reported on clinical trials which found that PTSD sufferers who used magic mushrooms as part of their therapy showed greater levels of improvement compared with patients who did not receive the drug.