SG 645a 1963 COMPAC 1/6d. strip of 3 with progressive ‘black omitted’. SUM

Great Britain  1963 Queen Elizabeth II Opening of COMPAC (Trans-Pacific Telephone Cable).  1/6d. blue and black.  Right marginal vertical strip of three with Sheet No. 02492 in margin.  Error on bottom stamp, ‘black omitted’ and almost completely omitted on middle stamp.  Superb unmounted mint condition.  Brandon Certificate No. 40,103 (2009). With photo showing position on sheet.  UNIQUE POSITIONAL EXAMPLE WITH SHEET NUMBER.  QUANTITY : 22.  EXTREMELY RARE.