"Of the couple of thousand stamps printed, only six of them had this special obliterator on, it's a speciality within a speciality."
The 1855 1d stamp printed by Perkins Bacon in London is a presentation copy to the family of Sir Rowland Hill, the inventor of the 1d Black postage stamp.
Obliterators help identify the post office of origin by encoding postmarks featuring a number, letter or letters.
Mowbray said the stamp would likely generate interest worldwide. There are 850 lots in the auction, with estimates of $1 million in total value.