Will Smith couldn't write his memoir until his dad had died

He said: “My father died in 2016. There were things in my childhood that I never would have shared while he was alive. I felt handcuffed in a way that I couldn’t share my full truth. He was one of the greatest men I’d ever known…but there were flaws.

“My father would have never been able to bear the conversation.”

The 53-year-old actor finally felt he had "suffered enough" to write his new tome 'WILL' and hopes it will be "helpful" to fans and readers.

Speaking to Idris Elba, 48, at WILL: An Evening of Stories with Friends at the Savoy Theatre in London, he said: “This was the first time when I [felt I] experienced enough, suffered enough and solved enough problems in my life…in order for it to be helpful.”

The ‘Fresh Prince of Bel-Air’ star believed his experiences gave him an “emotional authority”

He said: “It was the first time I felt like I could say things with an earned emotional authority that I thought could be helpful.”

And Will - who has son Trey, 29, from a previous relationship and Jaden, 23, and Willow, 21, with wife Jada Pinkett Smith - admitted writing the book had been a "cathartic" experience, even though it was hard to look back.

He said: “It’s so cathartic to get it out. It can be physically debilitating to not say your truth out loud… the practice of being even able to say it out loud is freeing.

“That self-exploration, to be honest with yourself and to move out into your life, your relationships...with that honesty, is excruciating. But I would recommend it.”

In the book, the 'Men in Black' actor admitted he considered killing his dad to avenge the abuse his mother, Caroline Bright, had suffered at her former husband's hands.

Although Will had retained a good relationship with his dad after his parents separated when he was a teenager, he admitted his anger from the childhood violence resurfaced years later while he was caring for his cancer-stricken parent.

He wrote: "One night, as I delicately wheeled him from his bedroom toward the bathroom, a darkness arose within me. The path between the two rooms goes past the top of the stairs. As a child I'd always told myself that I would one day avenge my mother. That when I was big enough, when I was strong enough, when I was no longer a coward, I would slay him.

"I paused at the top of the stairs. I could shove him down, and easily get away with it. As the decades of pain, anger, and resentment coursed then receded, I shook my head and proceeded to wheel Daddio to the bathroom."