E = Escutcheon

Escutcheons are found widely on many types of pillar box and wall box, they were intended to provide protection for the key hole. The collecting postman could turn a disc with two prongs located on the head of the key which would slide a cover over the keyhole, excluding rain and dirt. In practice they were rarely used and frequently got clogged-up when the box was painted.
The Letter Box Study Group
2016-02-10T16:05:39+00:00
Escutcheons are found widely on many types of pillar box and wall box, they were intended to provide protection for the key hole. The collecting postman could turn a disc with two prongs located on the head of the key which would slide a cover over the keyhole, excluding rain and dirt. In practice they were rarely used and frequently got clogged-up when the box was painted.