Correspondence was crucial during the Second World War, not only for military or governmental purposes but to maintain social morale. The British Post Office’s intention was that no letter should be delayed more than 48 hours due to enemy action. But from 1940, with the continuous bombardment of London, as well as other parts of the UK, this aim became more challenging. Frederick G. Gurr, a postman close to retirement in the City of London, was concerned that existing salvage squads did not recognize the importance of the mail; he set up the GPO Rescue and Salvage Squad to rescue mail, money and supplies from post offices and letterboxes bombed in London. Above is a hand stamp that distinguished mail delayed, but delivered.