Growing up in his rural Scottish village in the 1970s, John Phillips remembers his parents swapping their old black and white television set for a brand new colour version. The change was instant: colour and vibrancy were introduced suddenly into their living room.

Phillips, who has suffered from untreatable depression for eight years, says this is the best way of describing the experience of taking magic mushrooms, which he ingested during a highly-experimental medical trial.

“It’s like somebody throws a switch, and you go from being sat in the darkness to being sat in the light,” he says.

A former television consultant and Physics graduate, Phillips, 45, has suffered from crippling depression since his thirties, when he had to abandon his career after an accident left him with a brain injury. Forced to surrender his driving licence, he felt his purpose and livelihood sapping away.

“I suddenly realised that I might not be able to do the job I wanted to do ever again. It’s like your identity is removed from you. I felt like I wasn’t really worth anything any more.” His wife Maggie, with whom he had once enjoyed a healthy, co-dependent relationship, became his carer. Confined to his house for days at a time, he missed much of his younger son Reuben’s early life, unable to afford him the same attention he had given his older daughter Rebekah.