A slice of Princess Diana's wedding cake, kept untouched for 27 years in a former servant's attic, could sell for as high as 20,000 pounds when it goes under the hammer on Wednesday (today). The unique nine-inch square piece of cake icing and marzipan, which weighs 28 ounces, was given to cleaner Moyra Smith in 1981 when she worked for the late Queen Mother. Wrapped up in a metal tin the slice has remained in the loft of the London home of Moyra and her husband Donald ever since. On her deathbed Moyra, who died last month aged 78, revealed she had kept the royal cake and it was her dying wish for it to be sold to someone who would treasure it. The cake, along with a personally signed letter to Moyra from Diana, will go under the hammer at specialist auctioneers Dominic Winter Book Auctions, South Cerney, Wilts. In 1998 a similar slice sold for 17,000 pounds, a year after the princess died in a Paris road crash. Widower Donald said his wife had a special place in the hearts of the Royal Household. He said: "Moyra was an amazing woman. "Before she died Moyra told me that she had put some money away for me and our daughter Carolyn, but I didn't realise she had kept this for so long. "I found the cake in the loft, still wrapped in the same clingfilm she had put it in when she brought it home.' Donald, who would have celebrated 50 years of marriage to Moyra this year, said the find had brought back happy memories of his wife's time with the Royals. He said: "She worked there for five years in all, from 1981 to 1986, and we had some happy times." "When the cake arrived at Clarence House Moyra was told she could have a slice from the top tier to keep for herself." Diana memorabilia specialist auctioneer Chris Albury, from Dominic Winter, said the cake was the biggest piece he had ever seen. A personally signed letter from the princess thanking Moyra for her contribution to a wedding gift is also being sold in the lot. Chris said: "We are putting a value of at least 600 pounds on the letter because it is signed by Diana herself." "It has been personally signed by Diana to Moyra, which makes it very special. "Moyra donated 2,000 pounds for a minibus so I could drive groups for days out in Brighton and Bournemouth." - Daily Mail