The card was signed by Princess Diana

The signed pink card, bearing the message "Not many men receive a Valentine's card from Princess Diana", had been expected to fetch between �200 and �300.

It was part of a collection of gifts, letters and cards being auctioned by the widow of a former royal servant, Sergeant Ronald Lewis, which fetched a total of more than �49,000.

A spokeswoman for Cheffins Auctioneers said the firm was "surprised and delighted" by the sale.

Private collectors

"Virtually everything sold for more than we had expected.

"Letters we thought would fetch �100 to �150 fetched �600."

She said the buyers had been private collectors.

Before the sale, Simon Vickers, of Cheffins, told BBC Look East: "It's very unusual to get so much material all at once.

"Occasionally one or two items come up for sale.

"To get so many items from one source - so many signed photographs and letters and cards - is very unusual indeed."

Mr Lewis was once Travelling Yeoman for the Prince and Princess of Wales and his duties included making travel arrangements for the couple.

He died in 2001 after working for the royal family for 29 years.