1940 King George VI Centenary of First Adhesive Postage Stamps. Perforated Colour Trial for the 2½d. printed in red-brown (colour of 1½d.) affixed to card endorsed ‘C’ at top right and on reverse has manuscript ‘Shown to the King about 30.1.40). (wWith issued 1½d. and 2½d. for comparison). OUTSTANDING AND EXCEPTIONALLY RARE – BELIEVED TO BE UNIQUE.