Mood swings fuelled Heston Blumenthal’s genius. But the highs got higher and the lows got darker

“We just wanted a relaxing conversation with our dad and we weren’t able to have one,” says Jack Blumenthal. “It was horrible. And it was constant.”

Raw pain is etched on Jack’s father’s face as he finally realises how his undiagnosed mental illness – and erratic manic behaviour – hurt the ones he loves the most.

In a new BBC documentary, celebrity chef Heston Blumenthal is talking to his son for the first time about how he became impossible to live with.

“We’d plan it three weeks in advance, getting prepared just to see you for half an hour,” says Jack, who now runs a restaurant himself. “And there was nothing I could do to help you.”

Heston wipes a tear away. “I’m sorry,” he says.