Private boxes emptied by Royal Mail do not need to carry a cypher. Royal Mail post boxes manufactured given that 1994 carry the wording 'Royal Mail', normally above the aperture (lamp boxes) or around the door (pillar boxes). Just before this date all publish boxes, except for the Nameless pillar https://post-mounted-letterbox08742.suomiblog.com/letterboxes-melbourne-an-overview-43723668