More eerie remarks followed, with little Billy revealing he had two sons, and a brother named John - which was dismissed until David discovered Diana had an infant sibling named John, who died a year before she was born.
And then came the most jaw-dropping moment of them all, when Lisa showed Billy another photo of Lady Di.
“Billy said: ‘There’s me as a princess. Then one day the sirens came and I wasn’t a princess anymore’," David remembered.
"People shiver when we tell them this one.”
Campbell maintains his son has no knowledge of the monarchy, so his ability to recount these facts is spine tingling.
Speaking on TV the next day, David also talked about Billy's claim that spirits take him at night 'and bring him back by morning.'
He says he and wife Lisa have 'tested' their son's apparent knowledge of Diana's life, with uncanny results.
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