He is the nerdish genius who likes to think big and spend big –a visionary billionaire who will not rest until he has changed the world.

Elon Musk’s Tesla electric cars are already the leaders in the field. He is working on a vertical take-off electric supersonic aircraft and a ‘hyperloop’ transport system taking just 45 minutes to cross the American continent.

And he intends to revolutionise space travel with a master plan to create habitable colonies on distant planets.

Musk has started no fewer than four billion-dollar companies, so there is no doubting his talent or drive - and he’s happy to enjoy the fruits of his success, with three adjoining Bel Air properties, the obligatory private jet - and relationships with famously beautiful women, including actresses Talulah Riley and Amber Heard.

Yet there is one thing that even a £20 billion fortune cannot buy, and that is family harmony – in particular a warm relationship with his father Errol. Rarely shy of generating headlines, 46-year-old Musk has left the world in no doubt of where he stands, choosing to portray Errol in quite sensational terms.

Errol Musk last week at his home in South Africa. ‘Elon needs to grow up,’ he says now. ‘He needs to get over himself. I’m not going to hit back. I’m going to wait until he comes to his senses'

Elon Musk is pictured with his mother Maye Musk at the 2017 Vanity Fair Oscar Party

‘He was such a terrible human being, you have no idea,’ he told an interviewer for the American magazine Rolling Stone with tears running down his face.

‘My dad will have a carefully thought-out plan of evil. He will plan evil. Almost every crime you can possibly think of, he has done. Almost every evil thing you could possibly think of, he has done. It’s so terrible, you can’t believe it.’

It is hardly surprising, then, that the two men haven’t spoken for the past 18 months – not even ten months ago when 72-year-old Errol surprised his grown-up children by fathering a boy with his much younger new wife.

Throughout this turbulence, and despite his son’s international fame, Errol has maintained a dignified silence. Until now. For when he invited The Mail on Sunday into his elegant home overlooking a wide sweep of the rocky coast in South Africa’s Western Cape, he had some choice words about their incendiary feud – and made a shocking revelation of his own: he was once charged with manslaughter for shooting dead three men who broke into his home.

He was subsequently acquitted, after pleading self-defence. But it is an episode he speculates may be the reason for Elon’s cruel words.

‘Elon needs to grow up,’ he says now. ‘He needs to get over himself. I’m not going to hit back. I’m going to wait until he comes to his senses. He’s having a tantrum, like a spoilt child. He can’t have what he wants and now I am apparently an evil monster.’

A craggily good-looking man with a 1,000-watt smile and an easy humour, Errol still flies his own plane up the spectacular West Coast and has a fishing boat parked in the garage next to his silver Bentley Continental.

Errol Musk is pictured standing in front of a Tesla Model S in Colorado in 2014

A collection of family portraits is spread out on the handsome mahogany dining table: Elon with his brother Kimbal and sister Tosca, and their stepsisters Alexandra and Rose.

It is the very image of a happy family and, indeed, perhaps Errol and Elon have more in common than they would like to admit. Certainly, as Errol freely admits, the Musk family contains two huge egos, which clashed frequently during Elon’s privileged childhood.

Errol, a successful consulting engineer, and his first wife, former fashion model Maye, brought up their three children Elon, Kimbal and Tosca in luxury. Musk senior was a millionaire before the age of 30.

‘I drove them to school in a convertible Rolls-Royce Corniche, they had thoroughbred horses to ride and motorbikes at the age of 14. They were spoilt, I suppose. Maybe that’s why Elon is acting like a spoilt child now,’ he says.

Elon has described this childhood as ‘painful and isolated’, overshadowed by an absentee father who derided his eldest son’s budding scientific brilliance. Not so, counters Errol. ‘Elon has repeatedly told a story of me telling him computers were a waste of time. That’s untrue.’ Recounting early signs of his son’s intellect with genuine pride, he continues: ‘Elon has been generous enough to admit that he inherited his scientific genius from me.

‘When he was 11, he pestered me to pay a huge sum to let him attend a computer course where the first IBM PC, with mouse and keyboard, was to be presented for the first time. Groundbreaking stuff.

‘I told him to be quiet and well-behaved, to give his seat up to someone if necessary and sit on a step at the side of the stage.

‘When I came back after two hours to collect him, I found most people had left but a group had gathered at the foot of the stage. In the centre was my small son, his sleeves rolled up, talking earnestly. A professor listening to him turned to me and said, “This boy needs to get one of these computers.” ’

Elon Musk is pictured with ex-girlfriend Amber Heard. Errol said: ‘I think Elon was emotionally fragile when he attacked me. His girlfriend Amber Heard had dropped him and I believe he was crying for himself over the heartbreak'

Elon Musk with actress Talulah Riley

By the age of 15, in the mid-1980s, Elon was spending hours in his bedroom at a huge desk. ‘I came in one day and saw a grey box with a red light going on and off. Elon told me, “Dad, that’s a modem. I can connect my computer to a computer in Oxford, England. One day everybody will have one of these and they will all connect, all over the world.” ’

While Elon has complained his father subjected him to hours of lectures as a child, Errol claims these chats were to ‘pass on wisdom’. ‘South Africa has never been an easy place to live. In the 70s, it was a battlefield to grow a successful business.

‘Even my own mother called me ruthless in those days. We were all at each other’s throats looking for business. I also spent years in the military and that was hard in South Africa, where the world was frowning at everything we were doing.’

But Errol admits he was to blame for the divorce which split the family after 16 years of marriage.

‘I had a very pretty wife, but there were always prettier, younger girls. I really loved Maye but I screwed up.’

As the years went by, Errol watched from afar with pride as his son went from strength to strength, eventually attaining what his father describes as ‘the most remarkable job in the world’. By 2002, Elon had already made his first billion dollars from creating the PayPal internet payment system, and this was when he suggested that Errol and new wife Heidi come to live near them in Los Angeles.

The move was not a success. Heidi, who is Afrikaans, was unhappy to be so far away from her family in South Africa and, two years later, the couple moved back home. And that, Errol says, was ‘the first so-called terrible thing I did’. He believes his son took this as a personal insult.

‘Elon is upset with me,’ he says. ‘He is furious that he can’t force me to love America the way he does. I refuse to live there. I tried it, and came back home.

Elon Musk stands beside a rocket on March 19, 2004 in El Segundo, Los Angeles

Elon Musk poses for a portrait at in Los Angeles, California on July 25, 2008

Elon Musk is pictured with Peter Thiel in October 2000. By 2002, Elon had already made his first billion dollars from creating the PayPal internet payment system

‘He thought he knew better. America had made a successful inventor and scientist out of him and he believed it was the right place for all of us. Elon and his brother Kimbal were furious, like spoilt children with a total lack of human understanding about my situation.

‘They said they were finished with us. But Elon had done all the documentation for our new lives – and we couldn’t get our passports.’

Errol recalls feeling like a prisoner as he and Heidi plotted their escape, making secret appointments with the South African embassy to secure temporary passports. ‘I left everything behind. Elon disowned me, he said he wanted nothing more to do with me.’

Errol describes this episode as his son’s ‘Tantrum Number One’. But in time his attitude softened and, 18 months ago, Elon flew to Cape Town in one of his jets to throw a surprise birthday party for his father.

Then came Tantrum Number Two. ‘I got my 30-year-old girlfriend Jana pregnant and we had a baby son, who is now ten months old,’ he explains. ‘Of course, I love him dearly, even though it wasn’t planned. In my own cautious way I insisted on a DNA test to ensure he was mine. I told my daughter Ali about him because I thought she would be supportive and understanding. She said I was insane, mentally ill. She told the others and they went berserk. They think I’m getting senile and should go into an old age home, not have a life full of fun and a tiny baby.’

This, he believes, is what prompted the now-infamous outpouring of ire in Rolling Stone magazine. ‘I think Elon was emotionally fragile when he attacked me,’ Errol says.

Elon Musk’s SpaceX Falcon Heavy rocket takes off last month at the Kennedy Space Center in Florida

‘His girlfriend Amber Heard had dropped him and I believe he was crying for himself over the heartbreak. He describes me as terrible. But there are many things he doesn’t know – the work I did to lessen the effects of apartheid for so many years. I’d rather be in my home country, South Africa, with all its violent crime than live in the budgie cage of America,’ he continues, even though he has witnessed the violence at terrifyingly close quarters.

On one occasion he shot and killed three men in a group of burglars who smashed a window to get into his upmarket home in Johannesburg. ‘I was at home with my daughter Rosie, and the breaking of glass woke us up. I did what I had to do and we somehow escaped unhurt.’

He was acquitted of manslaughter on the grounds of self-defence. ‘That’s the only so-called terrible thing I’ve ever had to do,’ he says. ‘Maybe that’s what Elon is referring to.’

‘I’m not an evil person,’ he continues. ‘I have nothing to regret. I’m just a father who loves his son – and all his children – and is happy to know they are safe and healthy and secure.’

Today he has a beautiful young woman at home, and a baby boy whom he cuddles and clearly adores. Is it this same unquestioning affection that Errol craves from his eldest son, many miles away in America?

Or is there another, more troubling secret as Elon seems to hint – one which, for reasons of their own, neither father nor son can yet bring themselves to name?