Great Britain 1935 2½d Prussian Blue, SG456aGreat Britain 1935 2d Prussian Blue, SG456a. A superb unmounted mint, with full original gum, left hand marginal example of this key King George V famous error of colour. An exceptional example. Accompanied by a 2001 British Philatelic Association (BPA) Certificate of Authenticity. The Story King George V (known as the Stamp King) was a passionate stamp collector. So, on June 6th 1934, when he was asked for his permission for a commemorative stamp