His parents confirmed he was autistic after he passed away and that he had a history of seizures.

John gave an on-stage interview in London last night in which he spoke of his struggle to cope with Jett's death. He admitted there were times he "didn't want to wake up" after the tragedy.

"[It's] the worst thing that's ever happened in my life," he said.

"The truth is, I didn't know if I was going to make it. Life was no longer interesting to me, so it took a lot to get me better."

The 59-year-old actor spoke of how much his Scientology faith helped him in the months and years after Jett's death. It's a subject he's touched on in the past, with the actor giving details about the amount of help he was given during an interview earlier this month.

"I don’t think I could have got through it," he told British newspaper The Telegraph. "They were with me every day after Jett died. They even travelled with me when I needed to get away. And for a solid two years it was like that.

"It was only in the second year that I started to take a break of a day or two just to see how I was doing on my own."

During his talk yesterday, John explained his fellow Scientologists helped him learn ways to deal with grief and loss. It was only when he felt fully able to function on his own and with his wife Kelly and their other two children that the team left his side.

There were lighter moments during yesterday's interview with film critic Barry Norman too. John was happy to discuss his career issues, admitting he owes a lot to Quentin Tarantino. The director cast him in 1994's cult classic Pulp Fiction, which is widely credited with reigniting his career.

"It got a little complicated for a few years. A lot of things added up to a five-year period that wasn't so good for me," he said.

"There were people who were much hotter than me who wanted the role. But Quentin put his career on the line and refused to make the movie without me in it."

Fans were also invited on-stage for a dance lesson with the Saturday Night Fever and Grease star, who admitted he is in the process of trying to land a role as a bad guy in the next James Bond movie.