How friendly fire during WW II triggered the slow death of cash

On Sept 6 1939, three days after the declaration of war, a squadron of Hurricanes was scrambled from North Weald, Essex. Soon after, two reserves followed. But somehow, once aloft this pair were mistakenly identified as enemy aircraft. Spitfires took off from Hornchurch and shot them down. Frank Rose survived. But Montague Hulton-Harrop died, becoming the first British fighter pilot to lose his life in the Second World War – killed by friendly fire.

This accident intensified a secret project to develop a refinement that would allow radar operators to sort the anonymous dots on their screens into friendly and enemy craft. Led by Robert Alexander Watson-Watt, radar’s creator, a transmitter was built into Allied aircraft which broadcast a certain signal back, proclaiming it friendly. It became known as Radio Frequency Identification (RFID).

Eighty years on, that accident has claimed another victim. Cash. RFID is the technology inside debit cards, now slim enough to fit into a sliver of plastic. But it still does the same job, identifying the bearer via radio waves.