A slice of cake from the 1981 wedding of Prince Charles and Lady Diana Spencer sold for 1,850 euros ($2,558) at auction in Britain on Wednesday -- with a warning not to eat it.

The 40-year-old slab of marzipan and thick white icing decorated with the royal coat of arms fetched more than three times its asking price of 300 euros to 500 euros.

"We were amazed at the numbers of people wanting to bid on this large and unique piece of royal cake icing," said auctioneer Chris Albury, a royal memorabilia specialist at Dominic Winter Auctioneers in Cirencester, western England.

"There were lots of enquiries from bidders, mostly in the UK, the USA and several countries in the Middle East," he added in an email.

The successful bidder comes from Leeds in the north of England, Albury said.

The cake was originally given to Moyra Smith, who worked for Queen Elizabeth II's mother at her Clarence House residence in central London.

Following Smith's death, her family sold it at the same auction house in 2008 for 1,000 euros to a private collector, who has now sold it at a profit.

"It appears to be in exactly the same good condition as when originally sold, but we advise against eating it," the auctioneers said.

'Handle with care'

The cake remains as Smith kept it, wrapped in cling film in a cake tin that she labelled "Handle with care" and dated 29 July 1981, the day of the wedding.

The auctioneers said the slice came from a multi-tier cake served to staff at Clarence House, where Smith worked in the kitchen.

Apart from the main wedding cake, there were around 22 other cakes supplied by manufacturers for the royal occasion, the auctioneers said.

Wednesday's lot included order of service and ceremonial programmes for the wedding, a royal wedding breakfast menu and a table seating programme from Buckingham Palace.

Pieces of Charles and Diana's wedding cake still regularly go on sale and interest remains strong despite the break-up of their marriage and divorce in 1996.

A piece of wedding cake in an original commemorative box sold for $2,240 in the United States in December, according to Julien's Auctions.

The sale is the latest example of the continued fascination with Diana, who died aged 36 in a high-speed car crash in Paris in 1997.

In June, her old Ford Escort -- an engagement present from Charles -- was bought by a South American museum for more than 50,000 euros.

In 2019, a midnight blue velvet gown she wore when she danced with John Travolta at the White House in 1985 was put up for sale for between 250,000 euros and 350,000 euros.