A picture of a teenage Diana Spencer before she became Princess of Wales, with a young friend seated beside her, will be offered at auction.

AMHERST, N.H. — A picture marked “not to be published” that shows a teenage Diana Spencer before she became Princess of Wales, with a young friend seated beside her, will be featured in an auction in New Hampshire.

Stamped February 1981 on the back, the picture was taken around the time Charles, the Prince of Wales, and Lady Diana Spencer announced they were to be married.

The photograph came from the Caren Archive, a major private collection of rare newspapers and other publications, and was purchased seven years ago 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 young man in the photo. However, he said he understood that a British newspaper had been able to identify him.

British media have identified the young man as Adam Russell, the great-grandson of former Prime Minister Stanley Baldwin.

The auction is scheduled for Jan. 17-24 in Amherst.