only a few knowledgeable collectors are aware of the full significance of the plate numbers from this classic British stamp of yesteryear. Hidden within the borders of the stamp is the plate number and each number refers back to the original metal plate from which the stamp was printed. And as each plate printed different quantities of Penny Reds, so the plate number is the secret key to the stamps rarity and true value.
Maybe this might have something
http://www.pennystars.com/
One australian penny red sold for $48,400