Slice of cake from Princess Diana and Prince Charles' wedding is up for auction for up to an estimated $400

• Dominic Winter Auctioneers will auction a slice of Princess Diana and Prince Charles' wedding cake.
• The slice is from one of the 23 official wedding cakes made for the royal wedding in 1981.
• The cake was given to a staffer of the Queen Mother and later acquired by the auctioneer in 2008.

A slice of cake from Princess Diana and Prince Charles' wedding is going up for auction 40 years after the royal wedding.

According to the UK-based auction house Dominic Winter Auctions, the preserved slice comes from one of the 23 official cakes made for Diana and Charles' nuptials on July 29, 1981. The cake on display at their wedding weighed 225 pounds and was five feet tall.

The marzipan-based cake slice is covered in white icing with a red, blue, and silver sugared design of the royal coat of arms. The cake slice also has a silver horseshoe and a metallic overlay.

Dominic Winter Auctions says on its website that the cake icing layer was given to Moyra Smith, an employee to the Queen Mother at Clarence House.

"Moyra began her career at Clarence House in the kitchen before moving on to more general duties on the recommendation of Lady Jean Rankin. Besides the main official five-tier wedding cake, some 22 other wedding cakes were supplied by various manufacturers and this seems likely to have been one sent to Clarence House for the consumption of the Queen Mother's staff," the auction house continued on its website.

Dominic Winter Auctioneers' website says that it acquired the cake slice in August 2008 after it was sold on behalf of Moyra's family.

"It appears to be in exactly the same good condition as when originally sold, but we advise against eating it," the company added on the same webpage.

Along with the cake slice, the auction house is also auctioning off printed materials, including the order of the royal wedding, ceremonial details, and a breakfast program.

The auction is scheduled for August 9 and 10. The items are expected to sell between about $278 to $417 (£200 to £300).

Charles and Diana were married in 1981, and the couple later separated and formally filed for divorce in 1996.

A representative for Dominic Winter Auctioneers did not immediately respond to Insider's request for comment. A representative for Clarence House did not immediately respond to Insider's request for comment.