Royal Cyphers on Letter Boxes - The Postal Museum

What is “cypher-spotting”? A renewed interest in Royal Cyphers is making more people stop and take a second look at post boxes.

Ciphers - Letter Box Study Group

Stamps, coins and royal cyphers — Destination: History

Tradition and Design: The History of Royal Cyphers - Design Dives

People are only just finding out what the symbols 'GR' and 'ER' on postboxes mean

What Are The Royal Cyphers On UK Post Boxes?

Pillar box - Wikiwand

What does your postbox look like? - Mail, stamps & postal info

Point of Interest: Post Boxes

The King's Stamp Exhibition at the Postal Museum from 8 February to 3 September 2023 « London Visitors