The generous slice is from one of 23 official wedding cakes the royal couple served at their wedding more than 40 years ago.
It was initially expected to fetch between £300 and £500 but was met with a flurry of bidding from across the world. An internet buyer from Leeds secured the slice for £1,850. Auctioneers have advised the buyer not to eat the slice.
The slice was sold to Moya-Smith, a member of the Queen Mother’s household at Clarence House, in 2008. She preserved the topping with cling film and an old floral cake tin, labeled: “Handle with Care – Prince Charles & Princess Diane’s (sic) Wedding Cake”, signed and dated 29/7/81.
The cake’s auction coincides with what would have been their 40th wedding anniversary on 29 July.
It went under the hammer at Dominic Winter Auctioneers in Cirencester, Gloucestershire, on Wednesday afternoon.
Speaking after the sale, auctioneer and royal memorabilia specialist Chris Albury from Dominic Winter Auctioneers said: “We were amazed at the numbers of people wanting to bid on this large and unique piece of royal cake icing. It seemed to get far more attention than when we sold it with a Charles & Diana thank you letter 13 years ago.