During a visit to HMS Rothesay on Saturday August 22, 1987, Diana Princess of Wales accepted an invitation to carry out the traditional duty of 'stirring the Ships' Company Christmas Pudding'.
The implement she used was a wooden boat paddle which has been preserved.
It has been inscribed and is about 150cm in length.
Accompanying it is a mounted photograph taken on the occasion and a copy of the Navy News.
It was bought from Provenance an HMS Nelson auction in November 1997.
The lot is due to be sold at the Plymouth Auction Rooms in Cattedown and its estimate is between £500 and £600. The auction will also feature live online bidding.
For further information visit www.plymouthauctions.co.uk or call 01752 254740.