A long-lost photo of Princess Diana and David Bowie, taken backstage at a 1987 Wembley concert, has finally been unearthed. However, the reason it stayed hidden for decades is even more ...

Princess Diana and David Bowie at the Concert of Hope benefit for World AIDS Day at Wembley Arena in London on December 2, 1993. (Image credit: Tim Graham Photo Library via Getty Images) ...

Princess Diana and David Bowie at Wembley Arena in London for the Concert of Hope on World AIDS Day on Dec. 2, 1993. Princess Diana Archive/Getty Can't get enough of PEOPLE's Royals coverage?

Never before seen pictures of Princess Diana and David Bowie have been discovered 40 years after they were taken. The images were 'buried' after photographer Denis O'Regan received a 'polite ...

Music photographer Denis O'Regan has claimed that Kensington Palace held back his picture of Princess Diana with David Bowie after a 1987 London concert because she went to the show with James Hewitt ...

Princess Diana and David Bowie at Wembley Arena in London for the Concert of Hope on World AIDS Day on Dec. 2, 1993. Can't get enough of PEOPLE's Royals coverage?

Princess Diana and David Bowie at the Concert of Hope benefit for World AIDS Day at Wembley Arena in London on December 2, 1993. | Credit: Tim Graham Photo Library via Getty Images.