An intimate black-and-white photograph of Princess Diana as a teenager sold today for $18,396, a New Hampshire auction company said.

The photograph - which may never before have been seen by the public, RR Auction says - offers a glimpse of the future wife of Prince Charles lying down, perhaps on a bed, wearing a light sweater or top. Only her head and arms can be seen. Behind her a young man leans against the wall, reading, his book resting on her shoulder.

The only indication of date is a stamp on the back of the print saying "26 February 1981," which would be two days after the engagement of Diana, then 19, and Prince Charles was announced by Buckingham Palace. They married in July of that year.