A source who was on the same skiing holiday as the young Lady Diana when she was pictured relaxing with a friend has revealed to ITV News that the 'mystery man' pictured is Old Etonian Adam Russell, the great-grandson of former Prime Minister Stanley Baldwin.
According to the source, he was 'just a friend' of Diana and joined the large group of 21 on a holiday to the French skiing resort of Tignes, in 1979, he thinks, but says he struggles to recall the exact year.
The young Lady Diana joined the holiday late, according to the source, and was injured. That is when the picture was taken.
Watch Tim Ewart's report on the 'mystery man' on the News at Ten.
Royal biographer Andrew Morton told ITV News; "the picture was taken when they were both injured during the Ski Bob holiday which was organised by a number of Etonians. 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."
According to Morton, when they got back to London they kept in touch and in the summer of 1979 Adam completed his language degree at Oxford and decided to spend a year travelling.
Adam Russell is a deer farmer who now lives in Dorset.