Postage stamp
Postage stamps were first used in Great Britain on 6 May 1840, with the introduction of the world's first adhesive postage stamp, the Penny Black. Up until 1924, all British stamps depicted only the portrait of the reigning monarch, with the exception of the 'High Value' stamps, the so-called "Sea Horses" design issued in 1913, which were twice the size of normal stamps with added pictorial design.