During an appearance on This Morning, Piers revealed why people will be surprised when they watch the interview.
“He’s hilarious,” he said. “He’s sharp as a whippet. He’s got that Yorkshire grit and humour. He’s got a resilience about him born from his war years.
“[It was an] absolutely extraordinary two hours.
“Whatever you think you know about this guy, however you think he interacts, he talks – just be prepared to be surprised.”
Piers Morgan’s Life Stories continues tonight on ITV at 9pm.