AMHERST, N.H. — A photo marked “not to be published” that shows a teenage Diana Spencer before she became princess of Wales will be featured in an auction this month in New Hampshire.

Probably taken in 1979 or 1980 in a Swiss ski chalet, it carries the date of 26 February 1981 on the back. That was two days after the engagement of Diana to Prince Charles was announced, The Guardian reported. The photographer is not known.

The photo came from the Caren Archive and was purchased from the Daily Mirror newspaper. Bobby Livingston, vice president of RR Auction, said Saturday that neither the auction house nor Caren Archive knew the identity of the seated man in the photo. However, he said he understood that a British newspaper had identified him as Adam Russell, great-grandson of former Prime Minister Stanley Baldwin.

Diana and Charles divorced in1996; she died in 1997.

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