On 1 April 1680, William Dockwra, a London merchant, established a "penny post" service for London and Westminster. At the time, there was only one General Letter Office in London and Westminster to receive and dispense the mail; there was no provision for the general distribution of letters. Dockwra and his associates divided the urban area into districts with subordinate offices in each district. The principal office was Dockwras house. Every hour, messengers collected letters and parcels weighing under one pound in weight from receiving houses and took them to district sorting houses. From there, deliveries were made to local homes and businesses, often more than once a day. The cost of the service was one penny.
Dockwra is credited with the use of the first "penny post paid" handstamp. In addition, he used a time stamp that helped to deflect any criticism regarding claims of delays in delivery.
On 23 November 1682, the Dockwra penny post system ceased to exist as a private enterprise and was merged into the General Post Office.
Tom Hillman and Andrew Horrall
Robinson, Howard. The British Post Office, A History. Westport, Conn.: Greenwood Press, 1970, pp 70-76.