THIS IS THE FIRST STAMP IN THE SHEET (LETTERED "AA"), AND THE WATERMARK INCLUDES TWO PARALLEL LINES AT THE TOP OF THE STAMP - THESE BEING PART OF THE FRAME OF THE 240 LARGE CROWN WATERMARKS AS PER NOTE IN THE GB QV SPECIALISED CATALOGUE, QUOTE   ".....THE SPACE OCCUPIED BY THESE (WATERMARKS) WAS ENCLOSED IN A FRAME OF FIVE STRAIGHT WATERMARK LINES WHICH ARE OCCASIONALLY SEEN ON MARGINAL STAMPS"   THEY ARE QUITE DISTINCT - EVEN VISIBLE WITH THE NAKED EYE FROM THE FRONT AND BACK.  PLEASE NOTE THE MISSING CORNER PERF. AND A CENTRAL PIN HOLE,  NEVERTHELESS AN UNUSUAL WATERMARK VARIETY NICELY CAPTURED ON THE "AA" STAMP.  .