A lesson learned in a small ice cream parlour here more than three decades ago changed the course of a dragon’s life.

“There was a store here in 1973 called Magoo’s Ice Cream Parlour,” Dragons’ Den’s Kevin O’Leary recalled during an appearance at the Lincoln Fields Shopping Centre yesterday. “It was run by a woman. It was my first job, I was going to Nepean High School.

“We came back here today because I believed it was one of the seminal moments of my life.”

Young O’Leary had been working for several weeks when his boss asked him to scrape the gum off the floor with a screwdriver.

When he refused, she fired him.

“She fired me right over there,” O’Leary said as the audience laughed.

Although “it was so degrading to get whacked,” O’Leary said it was also a profound moment when he realized he would never be an employee again.

“I would be the employer,” he said. “I wanted to control my destiny. I don’t know where she is today, but I owe her a huge gratitude.”

The venture capitalist from the wildly popular television series — which launches its fifth season in January — yesterday shared the lesson his mother taught him, why he decides to invest, what every entrepreneur should know and the reason why the show is so popular.

“Dragons’ Den works because you’re watching real people pursue the dream of freedom,” he said. “That’s what wealth is — above all, it gives you a level of freedom that you can’t get any other way.”

He was only seven when his mother taught him the secret to preserving wealth.

“Never spend the principle,” he said. “Just the interest. It’s very hard to make the principle back.”

But at the same time, he’s not afraid to invest — if the opportunity and the entrepreneur are right. Aside from having a plan, a way to execute it and the knowledge of the numbers, entrepreneurs need to have “an aura,” he said.

“Do they have that magic, that je ne sais quoi, that makes you believe they’re going to be successful? That tips me over the edge. That’s what makes me write a cheque.”