STAFFORDSHIRE, England—An original cast of the portrait bust of the Queen of England that has appeared on more than 320 billion Royal Mail stamps since its debut in 1968 has been discovered in a cabinet in the artist's studio, reports the Times of London. The image, which the Times calls the most reproduced artwork in history, was created by the late Wedgwood designer Arnold Machin in 1966 and personally chosen by the Queen from among five works. The cast was found in a family home after Machin's son Francis died last year.

The 18-by-16-inch cast is one of only four surviving originals; it will be sold by Cuttlestones Auctioneers in Staffordshire on October 1 and bears an estimate of £10,000 ($17,800).