Princess Diana with Adam Russell in Mystery Photo from 1980s

By Kristin Boehm

01/04/2013 at 05:00 PM EST

Diana Spencer and Adam Russell

The Caren Archive

Leave it to royal reporter and Diana biographer Andrew Morton to reveal the "unknown male" in the 1980s photo of the late princess making the rounds Friday as it heads to auction.

Morton, who wrote Diana, Her True Story, was familiar with the image from when he was originally "given the task of trying to identify the boy in the picture."

"The young man was Adam Russell, the great-grandson of former prime minister Stanley Baldwin, and now a deer farmer in Dorset," Morton tells the U.K.'s Guardian of when he conducted interviews for his book.

According to Morton, both Diana and Russell were "injured during the skiing holiday ... They kept each other company while the others went skiing and, at the end of the holiday, Adam was somewhat smitten. But absolutely nothing happened."

They reportedly kept in touch, but eventually competition was just too tough for Diana's attention – who can compete with the Prince of Wales?

Now only the real reason why the Daily Mirror purchased then marked the image "NOT TO BE PUBLISHED" remains a mystery!