Dollis Hill Dummy Stamp with 4mm Violet Phosphor on re-used cover RARE

Originally used at Epson on the 15th of January 1966 (The dummy stamp was then removed) then re-used in London on the 21st of January with the Dummy Stamp applied. This item is illustrated on page 34 of the Dollis Hill Find. Ex The Edward Klempka Collection who was the Author of the DOLLIS HILL FIND