Private boxes emptied by Royal Mail do not need to carry a cypher. Royal Mail post boxes made given that 1994 carry the wording 'Royal Mail', Usually higher than the aperture (lamp boxes) or about the door (pillar boxes). Right before this day all publish boxes, aside from the Nameless https://judahrixne.blazingblog.com/26693483/letter-boxes-for-sale-no-further-a-mystery