"To a Scottish friend of ours, he claimed when he was Princess Diana he used to go to a castle in that kilted wonderland. He described the castle as having 'unicorns on it' and was called Balmoral," David shared.

Spookily, the unicorn is a national animal of Scotland, and Balmoral is adorned with the mythical creatures. David, who shares three children with his wife Lisa - nine-year-old Leo, and four-year-old twins, Billy and Betty - said his son's comments regarding Diana became more and more accurate.

Billy also insisted that when he was the Princess, he used to have a brother called John. David says he and Lisa were shocked when they went to Diana’s Wikipedia page.

"We turned pale. Diana’s infant brother John died a year before she was born," he said.

In possibly the most spine-tingling of all the details, avid shared that Billy had spoken of the moment he "stopped being a princess".

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"Lisa showed him another photo of Diana, and Billy said: 'There's me as a princess. Then one day the sirens came and I wasn't a princess anymore,'" he wrote, referring to Diana's death after a Paris car crash in 1997.

"Could he actually be the reincarnated essence of the People’s Princess?" David ended his column.

Watch: David Campbell's son claims he was Princess Diana in a previous life