Great Britain 1970 Queen Elizabeth II British Rural Architecture. 5d., 9d., 1s. and 1s.6d. The complete set in blocks of four. IMPERFORATE IMPRIMATURS. Superb unmounted mint condition. Handstamped ‘NP IMPRIMATUR’ on reverse and sent to the National Postal Museum for their Archives. ONLY 2 BLOCKS OF FOUR OF EACH VALUE WERE RELEASED INTO PRIVATE HANDS BY THE NATIONAL POSTAL MUSEUM IN LONDON (1984/85). AN EXCEEDINGLY RARE AND IMPORTANT EXHIBITION ITEM.