Black GR Post Office Letter Box. UK Editorial Image

On many postboxes, the clue to the meaning of these letters is on the postbox itself because you’ll often find these letters seen right next to a crown.The letters are called the “Royal Cypher” and they signify the King or Queen that was the monarch at the time when the postbox was erected.A GR post box was put up during the era of King George G stands for George, R stands for Rex, which is King in Latin. If there are no more letters around the GR, then it’s likely from the period of King George VGeorge V George Frederick Ernest Albert; 3 June 1865 – 20 January 1936 was King of the United Kingdom and the British Dominions, and Emperor of India, from 6 May 1910 until his death in 1936.