The star was among the VIP guests at the Virgin boss’ home on Necker Island when it was set ablaze by lightning from a hurricane.
She escaped with her two children – and famously also carried out Branson’s mother Eve.
Speaking about the incident on US television, Winslet said: “It was very frightening. The fire had taken hold by the time we had woken up.
Speaking to entertainment show Extra, she told of carrying Eve out of the house: “I just knew I had to get her out faster than she was able to go.
“I said, ‘Eve, I’m really sorry but I’m going to have to pick you up.’”