In his 20s, the son of Beatles legend Paul McCartney shunned his father, hated his new step-mother and descended into a dark world of drink and drugs.
When he turned to Class A drugs - with terrifying horse tranquiliser ketamine - even his sisters cut ties with him.
But that is now all in the past.
His father and the step-mother, one-time model Heather Mills, are divorced, and he has reconciled with his dad and he has found the confidence to finally perform the songs he has been writing since he was 17.
James admits his life was turned upside down when his mother Linda died of breast cancer in 1998 at the family’s ranch in Arizona.
“When I was 20 my mother died and I went off the rails a little bit. I kinda had my slightly dark period,” he says. “I got heavily into Nirvana, a bit of Marilyn Manson, these heavy bands. It was a kind of Goth thing.
“I was finding myself and I was drinking and doing a little bit of drugs.”
He smoked his first marijuana joint at 16 but after his mother’s death he admits: “I was getting high, mainly on cannabis.”
James’ increasing isolation worsened when his father met Heather in 1999. They soon began a relationship, later marrying, and it caused such a rift that James and Paul barely spoke for years.
He said: “It was a difficult time. Dad was married to Heather and we didn’t get on.
“I don’t have a problem with Heather now because she is Beatrice’s mum but at the time it was difficult for me, I was so into Kurt Cobain and this mentality so I didn’t really like her. It was very difficult, I had my own issues.
“I was also pretty sceptical even of Dad being so commercial, but now I really embrace that, it’s amazing what he does, it’s really rock and roll.
“We drifted quite far apart, it was a difficult period. It was a coming of age for me. I had to strike out on my own and I needed a bit of time to grieve my mum’s death.”
James was living in Brighton, waiting on tables, and while his sister Stella was forging an international career in fashion, he descended even further into a life of drugs.
Now, sitting in his Nashville hotel, where he is performing two nights at the legendary Bluebird Cafe, James is matter of fact about his lost years.
He said: “The estrangement was partly because of Heather. It was difficult because of Mum’s death and then moving on, having a new mother.
“I started getting more into Class A drugs, ketamine. I wasn’t doing heroin but it’s practically like heroin... but not quite the same.
“It’s not that big a deal… but it is at the same time. It was my mistake. It wasn’t a problem, I think it was just once, it wasn’t that bad.
“All the family were concerned for me, they were worried. But it got to the point when they were just: ‘effin let James do his own thing.’
“At the time I severed that tie with the rest of the family a little bit which I wish I hadn’t done now “
James went into rehab in Arizona but left shortly afterwards.
His relationship with his father suffered and James admits: “I went a long time without seeing Dad. We drifted apart. We would talk on the phone every few months but we went a long time without seeing each other. It was sad for both of us.”
But, when his father had heart problems and went in for surgery to open several blocked valves in 2007, a year after splitting from Heather, he realised how important his father was to him.
The spiritual singer, songwriter finally turned a corner when he saw a vision on the family farm in Sussex that felt like his mother Linda.
“The climax was more of a drugs thing. I started doing heavier drugs but it wasn’t an overdose or anything like that” he says.
“I had that dark period and then hit a bit of a climax. I thought ‘I need to be responsible now, I am 30 years old you can’t just keep doing this’.
“My darkest moment was when I saw the light. I don’t want it to sound cheesy, but I was in the dark quite a lot, literally, I was in the woods and I saw an ethereal light shining. I knew it was meant for me.
“Dad was in the press saying he had a bit of a heart flutter. Then we started talking a little bit. It was difficult for everyone at that time but some good came from it.”
It was the beginning of a tentative reconciliation which has now transformed their relationship. “Dad’s great now but that episode made me realise how important he is to me.” says James.
He has been sober for several months now and is working hard on his music career. More importantly, he has rebuilt the bridges to his father and sisters Mary and Stella.
“They are happy that the ties are back now and with Dad, we are great mates now” he says. “I definitely want to embrace the relationships I have with the people I love.
“Especially someone like Dad, who is my dad and he is also my best friend.
So what about the ex Mrs McCartney?
“I never see Heather but if I ever did see her I would have full respect because she is Beatrice’s mother” James says.
“His new wife Nancy is great, she’s lovely and Dad’s happy. It is difficult to replace mum but Nancy is beautiful and wonderful.”
It is clear the whole family has embraced the new addition.
“Nancy’s my new mother. I feel that. Definitely. She’s very genuine.” says James. “She makes Dad very, very happy. We all adore her.”
Despite his father’s worldwide fame, Paul tried as best he could to give his children a normal upbringing. Instead of a private school, Paul sent his children to the local.
But the real world was never far away.
James said: “I was born in ‘77 and then John Lennon was shot in ‘80 and that totally knocked dad for six. I haven’t really spoken to him a lot about it because it is probably such a touchy subject, obviously.
“I was a little baby then and for a while Dad really didn’t tour after John was shot.”
But he admits growing up as the son of one of the most well-known people in the world wasn’t easy.
“It wasn’t truly normal; it couldn’t be, because of the level of fame. My dad had a normal upbringing and I think he then wanted to introduce a normal upbringing to us as well, so we went to a comprehensive school.
“Everyone at school knew who my dad was. It made me a little self-conscious a little introverted because I had a lot of attention drawn towards me, but in a way I guess it gives you a little bit of a celebrity skin, even though I wasn’t a celebrity.
“There was a little bit of bullying, just a little bit. I got the same thing as everyone gets really; all kids get bullied a little bit. I got jokey nicknames like Macaroni. Then I had good nicknames like Car – from McCARtney.”
Not surprisingly, music formed a great part of his childhood. Like his dad, James taught himself to play the guitar and piano and he began writing songs at an early age.
He says: “I think having a father like Dad it was hard not to get into music.”
But Paul’s footsteps were always going to be difficult to follow.
"It’s hard to live up to the Beatles” says James. “When Wings toured they got slated. Even Dad found it hard living up to the Beatles. I started out playing under an alias.”
After a stint making furniture, James started out known as ‘Light’. Now happy to perform under his own name, he has released his first album, Me.
Performing at the Bluebird, James poignantly dedicates the song Bluebell to his mother.
He says: “All these songs are about different things. I am not sitting down going I want to write a song about Mum but I mean, they just flow and they come, it’s sort of like a therapy…
“When my mum died my dad said to her as she passed ‘you are riding on Blanket through the bluebells’, Blanket was her horse at the time.
“They were my dad’s last words to Mum and the song came from that.
“Mum was very cool. Even though she came from a pretty affluent family, she was cool. She was really good, a very normal person.”
James is in a good place right now. He is nearing the end of a hectic American tour, which comes to London on July 4, to support his new album.
But most of all he has regained his family and that, it seems he has realised, is far more important.
- James McCartney’s Me is out now.
By Alun Palmer