The teenage son of Australian musician Nick Cave fell to his death after taking the hallucinogenic drug LSD, an inquest in England has heard.

Arthur Cave, 15, suffered a “catastrophic” head injury after plunging from a cliff in Brighton, East Sussex, on July 14.

Witnesses described seeing the student “walking, staggering and zig-zagging” before standing “dangerously” close to the cliff edge moments before he fell.

Arthur and a friend – who can’t be named for legal reasons – had earlier taken LSD, also known as acid, an inquest in Brighton was told.

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Members of the public tried to resuscitate him after he was found lying on the underpass of Ovingdean Gap without any shoes or socks, but he died later at Royal Sussex County Hospital.

Veronica Hamilton-Deeley, senior coroner for Brighton, on Tuesday recorded a conclusion of accidental death.

She said: “I expect the decision and planning to take LSD, or a hallucinogenic drug likely to be LSD, was made on the spur of the moment.”

“It’s clear he could not know what was real and what was not real. It’s completely impossible to know what was in Arthur’s mind and what he was seeing,” she said.

Cave and his wife Susie briefly walked out of the courtroom before graphic details of their son’s injuries were read out from a post-mortem examination report.

The coroner said the cause of death was “unsurvivable head injuries due to a witnessed fall from a cliff”.

The teenager, who lived in Brighton, was found on Undercliff Walk. Photo: Getty

A contributory factor was the recent ingestion of a hallucinogenic drug.

The boy who took LSD with Arthur said he researched online about the effects of the drug but had not read anything about the “darker side”.

The pair had arranged to take the drug on a grassy area near Rottingdean Windmill in Brighton.

In a summary of the boy’s statement, Detective Constable Vicky Loft the court: “Arthur was hesitant but said if they were worrying about things it would have an effect on the trip and make it a more negative experience.”

“They decided to take one together at the same time. They took a tablet each, placed it on their tongue and waited for the effects to start,” she said.

The boy said he and Arthur took three tablets between them and they were initially in “good spirits and happy”, but he then started having “vivid hallucinations”, including seeing patches of oil on the grass and shapes and colours in the sky.

Det Const Loft said: “(The boy) became paranoid and felt like people were staring at him in cars. He couldn’t tell what was real and what was not real.”

“He thought he could see Arthur covered in vomit but wasn’t sure if it was real.”

The boy said he was not sure if he and Arthur walked off together but he recalled they went their “separate ways”.

Cave, who clutched a tissue during the inquest, hugged his wife after the hearing.

In a statement issued later the Cave family thanked the coroner, medics who treated Arthur and members of the public who helped at the scene.

They said they’d been overwhelmed by the many messages of support since.

“Arthur was a wonderfully unruly, creative and free-spirited young man with an infectious, happy, funny daredevil nature,” the family said.

“He loved his friends and family, idolised his twin brother Earl and was never far from his side. And we loved him back – to his core – and we miss him deeply.”