The cultural icon was 24.

In 1977 interview on the BBC's Parkinson Talk Show, unearthed by Heat Vision, a somber Guinness recalls how he warned the young man that if he drove that car, he would be killed. That conversation took place the evening of Sept. 23, 1955, just one week prior.

It all happened when Guinness and a friend were turned away from a packed restaurant in Hollywood, so they began to head elsewhere.

"Then I heard feet running down the street, and it was James Dean," Guinness began. "He said, 'I was in that restaurant and you couldn't get a table. My name is James Dean, would you please come and join me?'"

At the time, Guinness had numerous film credits to his name and an Oscar nomination for The Lavender Hill Mob, so clearly Dean knew he was a big deal.

Guinness and his friend agreed and started back, but before they went inside, Dean wanted to show off his new car, Guinness recalled.

"There in the courtyard of this little restaurant was this little silver thing, very smart, all done up in cellophane with a bunch of roses tied to its bonnet," Guinness told Parkinson, adding that he asked how fast it could go. Dean replied it would do 150 mph.

"I said, 'Have you driven it?' and he said, 'No. I have never been in it at all,'" Guinness said. "And some strange thing came over me. Some almost different voice and I said, 'Look, I won't join your table unless you want me to, but I must say something: Please do not get into that car, because if you do' — and I looked at my watch — and I said, 'if you get into that car at all, it's now Thursday (Friday, actually), 10 o'clock at night and by 10 o'clock at night next Thursday, you'll be dead if you get into that car.'"

Dean brushed the warning off and the group proceeded to have a "charming dinner," Guinness told Parkinson.

"And he was dead the following Thursday afternoon in that car," said Guinness, who died in 2000. "It was one of those odd things. It was a very, very odd, spooky experience. I liked him very much, too. I would have loved to have known him more."

In September 2015, The Hollywood Reporter reported that to this day, people still visit the crash site and leave an assortment of tributes, including pictures, alcohol and women's underwear.

The spot is referred to as "Blood Alley" due to the number of fatal crashes that still occur there now.

Watch Guinness' revelation below.