The earliest postmark, devised by Henry Bishop, the first Restoration Postmaster-General, to indicate the day and month that the letter was received at the post office.  The exact date on which it was introduced is not known; but the earliest surviving examples date from May 1661.  Bishop himself wrote: 'A stamp is invented that is putt upon every letter shewing the day of the moneth that every letter comes to the office, so that no Letter Carryer may dare detayne a letter from post to post; which before was usual.'
 
 
 

- R. J. Sutton 6th edition revised by K. W. Anthony
The Stamp Collector's Encyclopaedia

Published 1966

Posted March 26, 2000