Street Lights powered by sewer gas!

Can't remember if I had shared these pictures before but if you go up the lane behind the Savoy Theatre in London, walking up from the Victoria Embankment, you can see this street lamp lit by sewer gas from the Bazalgette main collector sewer which runs along the Embankment immediately behind the embankment wall, before the underground train line which is also hidden away below the road.

To complete the story, walking to the gas lamp from the river I came across at Thames Water team preparing to enter what I guess must be an offshoot of the main sewer just 50 metres away. With excellent health and safety preparations!