Utilising the cheap and plentiful coal tar that was an almost unlimited byproduct of London's gas street lighting, the dye works began producing the world's first synthetically dyed material in 1857.

Using reams of blinking LEDs for street lighting may save energy, but clashes horribly with the pretty architecture of old Shanghai.

The schemes to reduce street lighting involve either switching some off altogether or installing new lamps are automatically dimmed or turned off during "quiet" periods, late at night.