Great Britain 1935 2½d Prussian blue, SG456aGreat Britain 1935 Silver Jubilee 2d Prussian Blue, SG456a. A superb used example of this rare error of colour beautifully cancelled by a crisp Westmead Corner Carshalton Surrey circular date stamp for 24. 7. 1935. Accompanied with an example of the normal blue colour for comparison. The Prussian Blue is the most iconic error of colour in GB philately, affectionately known as the "King's error". Used examples of the Prussian Blue are particularly