NEW YORK (CBSNewYork) – It’s hard to believe, but there’s a never-before-seen photo of the late Princess Diana.

The photo was taken while she was on vacation in Switzerland when she was 18 or 19. It shows her lying on a bed with a unidentified male friend who’s resting a book on her shoulder.

READ MORE: Brian Laundrie: Who Is Gabby Petito's Fiancé, And What Do We Know About Him?

The photo was sold to the Daily Mirror in 1981, two days after Diana and Prince Charles got engaged. The paper’s editor wrote on it “Not To Be Published.”

READ MORE: Fighter Jet Intercepts Small Plane Flying Over NYC After Biden's UN Speech

The photo remained in the paper’s archives until 7 years ago, and is now up for sale through RR Auctions in New Hampshire.

MORE NEWS: At Least 2 Injured When NJ TRANSIT Bus, Car Crash In Irvington

The photo is expected to fetch over $1 million. The bidding will be held online Jan. 17-24. A preview of the auction can be seen by clicking here.