AUSTRALIA 1951-52 7 1/2d blue, block of 16 being the upper two rows of the left pane with full margins, the left vertical pair error IMPERFORATE THREE SIDES as a result of the omission of the first strike of the comb, very fine such unmounted o.g. from a sheet purchased at a Sydney suburban post office early in 1952, which was separated into five such blocks, although two are now known to have been reduced to blocks of 4, a spectacular showpiece of the highest rarity (Image)