On the first of May 1840 the first British Penny Black stamp went on sale. Invented by Sir Rowland Hill, it was the world’s first adhesive postage stamp and it became valid for postage on 6th May. The idea of an adhesive stamp, which would indicate pre-payment of postage, was part of Sir Rowland Hill's proposals in 1837 to reform the British postal system. Until then our ancestors would pay postage on delivery of their mail. Another idea that Sir Rowland suggested at a government enquiry on February 13, 1837 was for customers of the service to use a separate sheet that folded to form an enclosure or envelope for carrying letters. At that time postage was charged by the sheet and on the distance travelled.