Princess Diana wedding cake
The 33 year-old slice of the Royal Wedding cake is still wrapped in its original wax paper and gift box.(Nate D Auction House, Los Angeles)

A slice of cake from the wedding of Princess Diana and Prince Charles – who were wed 33 years ago – has sold at auction for $1,375 (£830, €1,040).

The cake, sold online on Thursday through an auction house in Los Angeles, is still in its original silver and white presentation box.

A card inside the box says, "With best wishes from Their Royal Highnesses, the Prince & Princess of Wales."

Sam Heller, a spokesman from the Nate D. Sander Auctions of Los Angeles in California says the buyer is a private collector.

Heller says although the cake came wrapped in its original wax paper, it probably "wouldn't be a good idea" to try and eat it.

He added that there is a small, but dedicated, group of collectors of royal wedding cake.

Some, Heller says, have purchased cakes dating back to the reign of Queen Victoria, who married in 1840.