Royal biographer Lady Colin Campbell has revealed that she will release a 'tell-all' book on Prince Harry and Meghan Markle this summer.

The 70-year-old - famed for her combative stint on I'm A Celebrity, Get Me Out Of Here in 2015 - has previously written controversial books on Harry's mother, the late Princess Diana.

Harry and Meghan stepped down as senior members of the Royal Family earlier this year and are planning to release a book about their decision, Finding Freedom, in August.

According to the Daily Mail, Lady C has been working on her own book about the couple and plans to release it around the same time.

"It's called Meghan And Harry: The Real Story," she told the newspaper. "There are plenty of revelations. I've had members of the Markle family to stay, but I'm not saying anything until closer to the book launch."

Lady C has also previously written a book on Harry's great-grandmother, the late Queen Mother.