Memorial

Near this spot the General Letter Office stood in Post House Yard, 1653 - 1666. Here were struck in 1661 the first postmarks in the world.
{There is then a symbol about the size of a capital letter: a circle divided with a horizontal line with "AP" in the top half and "19" in the lower half. This is the post mark for 19th April the date postmarks were first used.}
The Corporation of the City of London