Sinéad O'Connor has written an open letter to Prince Harry.

Prince Harry

Prince Harry

The 54-year-old singer was moved by Harry's recent Apple TV documentary on mental health, 'The Me You Can't See', with Oprah Winfrey and believes his late mother, Princess Diana, would be very proud of him.

Writing in Ireland's Sunday Independent newspaper, Sinéad said: "As someone who has trauma-related mental health struggles, I wanted to let you know how bowled over I am by your Apple TV series. You're slammin' it, to use a musical term. You just keep shining on through."

Sinéad revealed that she identifies with Harry's grief over the death of his mother Princess Diana in a car crash in 1997 when he was just 12, as she lost her own mother in similar circumstances when she was 18.

She explained: "I'm writing this because you and I have something in common Harry. I also lost my mother in a car crash... I do know something of the grief you've been brave enough to share in the public arena. It's a shock that takes years to come out of, when someone dies so violently and suddenly. It's a lifetime's recovery.

"I really identified with you when you shared the rage and anger you felt at the time of your mother's passing. I was the same. I'm sure we all were, any of us who ever lost someone in that sudden way. Transcending that grief as you've done by sharing it, cuts through a lot of garbage. And a lot of us appreciate what you're doing."

And Sinéad went on to tell Harry, 36, that his mother would be very proud of him.

She wrote: "When so many of us see the work you're doing for people who experience mental health struggles, we see you stomping on stigma. And we're all delighted for you. Most importantly, we know how proud your mama is of the incredible young man you are."