An STC 4035 microphone, made by Standard Telephone and Cables Ltd, about 1950. Modified for broadcasting the chimes of Big Ben, with a special mounting spigot fitted on the back for use directly below the bell.
When the BBC first started in 1922, the hourly chimes were actually played by the announcer on a set of chime bells in the studio. But Big Ben itself was broadcast to usher in 1924, and later, a microphone was installed inside the clock tower and connected directly to Broadcasting House. This moving coil microphone is one of a number that were used over the years and its low sensitivity allowed it to be installed right by the bell. Engineers experimented with microphones placed further away, but these picked up the sound of the clock mechanism and even London traffic.