Rod, this area was heavily bombed during WWII. There is a listed building at the corner with Cheapside for which the records state it was damaged during the war. Google Maps' street view shows some modern buildings. This post office may have been destroyed during the war.
Interesting suggestion NSK, and valid,
do I recall Perkins Bacon was also bombed ? And certain plates and information failed to survive.
That said, it should appear in written records, somewhere, but very notable in its absence.
I am tempted to write to the GB Phil society.
The 2 glaring queries for me, in this thread.
Where is the information on King Street BO ?
Where is the information on numbers of the sub offices, identified in Ron's post
This MUST exist somewhere.... I want it
Basically, when registration labels were introduced in 1907, town sub-offices were identified on the labels by the name of the town (or London district) and a sub-office number (allocated by the local head postmaster according to whatever system seemed best to them). So in this case 19 is simply the sub-office identifier in London E.C. for the King Street office.