Britain issue KGV 2 1/2d with o/p of 1 piastre. Have been searching in the net and found this stamps were issued 1904-1912.The British KGV with piastre o/p were used in a few countries mainly middle east.How can I pinpoint exactly the year of issue of this stamp and the country it was used in. The postmark (image 2) states only as British Post Office.Thanks for the advise and opinions guys.

