Edward VIII In Clevedon
In total, there are about 115,000-116,000 postboxes nationwide. Of these, only about 160 survive which bear the mark of Edward VIII (E8R). This is due to the short-lived reign of this particular monarch, back in 1936.
Here are two of them, both situated in Clevedon. Nearby Bristol, by way of comparison, boasts just three surviving examples.
Many thanks to yercombe for invaluable assistance.