6p Cylinder Proof

1972 6p FCP PVA Cylinder 4. (Phos 1) Cylinder torn from a master double pane. Proof sample suplied by Harrisons the printers from thier Bedford Street London office, to the then editor of Stamp Collecting Barbera Baker as a sample of what was going to be issued. The dot cylinder would normally have been guillotined from no dot, thus this block, and other values I have, are unique examples