Received several letters today from Great Britain with interesting postmarks. Royal Mail web site describes what is going on. Hats off to Royal Mail for the postal history -- in the days of yore before postage stamps. And this is why I collect postmarks as well as stamps.
"Royal Mail is commemorating the introduction of the Bishopmark â€“ now known as a postmark - 355 years after it was first used to ensure that mail was delivered in a timely manner.
The stamp was introduced by Colonel Henry Bishop, the first Postmaster General, on 2 August 1661 and featured the day and month when the item of mail had entered the postal service
To mark the day Royal Mail is releasing a special postmark that replicates the design of the original.
The UK was the first country in the world to use a date stamp. Since then, the concept has been replicated across the world.
The commemorative postmark will be applied to stamped mail nationwide from Tuesday 2 August to Saturday 13 August 2016"