gpo[24] / whn[24] - postbox

Red "Pillar Box" in the Market Place at Whitehaven.
The cast monogram is George VI who reigned between December 1936 and his death in February 1952.
Note Also the cast "Post Office" who dealt with the Royal Mails until the idiotic partial privatisation in 2013, the government sold off the remaining 30% stake in 2015, which ended 499 years of public ownership.