GB Edward VII 1d trial stamp proof pane of 25 in blue on zig-zag watermarked, gummed paper. Reportedly produced by Bruckman of Munich, the German printing house as a sample to tender for postage stamp contracts using their new Heidelberg machines. Printed in 1931, the stamps were oversized and used the previous king instead of George V to protect against their use as postage. One of 24 reported sheets (total 600 trial stamps). Retail £3,120. (Image)