When streetlamps were first introduced in London and other cities they didn't have electricity to power them and were powered by gas. Thousands of lights were lit every night by a fleet of people with long poles - with a flame or lighting device attached to the end .And i guess they came around at daylight and turned of the gas to extinguish the flame. The lamp in this photo now runs on mains gas, but for years it ran on gas from sewer waste. London's underground sewers created lots of methane which is flammable, It actually served two purposes- methane gas has a nasty rotten egg smell and it often seeped from the sewers.By siphoning off the gas and burning it, it solved this problem and created a cheap supply of gas. Unfortunately the gas light would often go out due to not enough gas from the sewer and the gas would escape from the lamp causing a nasty smell. This lamp is in Carting Lane behind the Savoy Hotel in the Strand -a posh area of London- so the residents were not too happy about the smell,and it was nicknamed Farting Lane. The problem was eventually solved by using mains gas along with the recycled methane,The mains ensuring the lamp stayed alight and the methane continued to be burnt and eliminated the smell.Modern day sewers don't have these problems now as they use electric extractor fans.