The blackout in Britain began in 1939 after earlier trials by the RAF, with certain towns attempting to maintain a blackout. One of the biggest risks identified was lights on vehicles.
New measures were brought in and in the case of our lamp, the following applied:
'In the case of lamps carried by pedal cycles, the following rules must be observed:
The upper half of the front glass must be completely obscured;
The lower half of any reflector must be treated with black paint or otherwise rendered non-effective;'
The blackout led to a dramatic rise in road accidents. The King’s Surgeon, wrote in the British Medical Journal in 1939, complaining that by “frightening the nation into blackout regulations, the Luftwaffe was able to kill 600 British citizens a month without ever taking to the air”.