Malta 1926 4d Misplaced Overprint, Rare Block

1926 4d MISPLACED OVPT (SG 150var) F/UM top left corner block of four showing grossly misplaced overprint. Light foxing spots on reverse as with all stamps of the single part pane affected. Exceptionally attractive error. Rare & spectacular exhibition piece. (Malta Study Circle mentions "Two mint blocks of four are known", whilst this is in fact the third such block we record).