Great Britain 1978 9p Cycling error, SG1067aGreat Britain 1978 9p Cycling error, SG1067a. A superb unmounted mint, with full original gum, imperforate top marginal block of four showing central sheet ornament in margin. A scarce QEII imperforate error. Pierron records only two imperforate sheets discovered in Sutton giving a total of only 50 mint pairs possible. Exceptionally rare as a block of four. The stamp issue commemorated the Centeneries of Cyclists' Touring Club and British Cycling