Great Britain 1971 Queen Elizabeth 100th Anniversary of Rugby. 9p. multicoloured. Right marginal example. Error, ‘new blue omitted’. Superb unmounted mint condition (with normal for comparison). British Philatelic Association Certificate No. 76,044 (2010). AN EXCEEDINGLY RARE AND IMPORTANT ERROR OF WHICH ONLY 10 MINT ARE KNOWN. AN EXHIBITION PIECE.