Jon Snow describes moment he got stoned on 'two huge balloons' of skunk – and 'terrifying' four-hour come down

The C4 News presenter experimented with the drug for a new series

“What was happening to me outstripped anything I have ever experienced,” Jon Snow said of the point at which he knew he was high.

Properly high, he added, detailing the “one or two” times he’d been passed a joint of cannabis at a party (and missing out the entire blog he’d written about driving up the M40 on LSD following an incident with a spiked flan when he was a student at Oxford).

He had, he said, lost “all sense” that he was in a small lab room somewhere behind University College Hospital, where he took part in a Home Office-approved, NHS-supported trial of skunk, being filmed for Channel 4’s Drugs Live programme on 3 March.

They’d decided to test the drug on human Guinea pigs following reports that 25 per cent of all psychosis treated in Britain is associated with smoking skunk.

But the worst was yet to come for Snow. He was too tall for the MRI scanner scientists were using to track the effect skunk was having on his brain.

“The mask over my head kept catching the top of the inside once I’m pushed in,” he wrote in his blog for Channel 4. “The terror in me kept rising, my panic chasing hard behind. When you see the film, you can here this distant voice wailing ‘I can’t stay in here…let me out!’”

“I’ve worked in war zones but I’ve never been as overwhelmingly frightened as I was right then,” he added.

But in among the haze, there was a small creative positive to be had.

“Just toward the end, I felt a sense of euphoria and expressed it by drawing a pastoral scene on an old box that was lying around in the lab,” he wrote. “I drew trees, a fence, a river, and a couple of people – perhaps the very people, trees, and water, that I had felt so deprived of whilst stoned.”