GB 1840 Penny Black attractive used *INVERTED WATERMARK*. Under 20% of SG!: "

[Jozef.]

"The World's First Inverted Watermark!" In over 40 years of stamp dealing I have NEVER owned an INVERTED WATERMARK of these. Never. They are RARE. Have sold probably 1,000++ x non inverts. Clean and fresh. TOTALLY free of the hinges and gum and toning and creasing etc, that often be-devils this issue, so the INVERT shows as clear as a bell.

https://www.stampboards.com/viewtopic.php?f=27&t=92583