Jamaica SG5 6d Dull Lilac Wmk Pineapple Cancelled with English 51 postmark

From time to time letters were received in England from Kingstone bearing uncancelled stamps. The majority of the few examples received in this state were cancelled at Bristol or Falmouth and thus bear a B or F in a diamond surrounded by thick horizontal bars forming an upright oval. In the rare event of their not being cancelled at the above mentioned place they were cancelled at the Foreign Department of the Post Office in London. They used three numerical obliterators for this purpose (43. 50 or 51 in a square shape surrounded by horizontal lines forming a circle). The stamp has some toning.