Great Britain 1925 British Empire Exhibition first day cover, SG432/3Great Britain 1925 British Empire Exhibition first day cover, SG432 3. A very fine used set of two tied to a clean envelope by a crisp Empire Exhibition, Wembley Park slogan machine cancels for MY. 09. 1925, the first day of issue. A most attractive first day cover and very rare. The British Empire Exhibition stamps were the first ever commemorative stamps issued by Great Britain. These became affectionately known as The Wembleys. The British Empire