A plaque on Bridge Street facing the Palace of Westminster credits the installation to inventor John Peake Knight.

The traffic light stood 6m high and featured red and green lights. It was said to resemble a railway signal with waving arms to indicate the need to stop. At the time, more than 1000 people were dying on London’s roads every year, despite there being no cars on the road.

According to Transport for London, the signal was powered by gas and required police constables to change the light manually using switches. But it was removed only a month later, after a policeman was reportedly seriously injured in a gas explosion. Traffic lights did not return to the capital until 1926.

Today there are more than 6000 traffic lights in the capital. Transport for London is currently working to retime many signals to reduce the time spent by pedestrians, cyclists and bus passengers waiting at junctions.

This includes work at Marylebone Road where crossings are split into two to improve the link between the timings to avoid people having to wait in the middle island. Recent improvements at junctions for those on foot have been introduced at York Road in Wandsworth, to parts of Oxford Street and at High Road in North Finchley.

Transport for London has also worked with Living Streets to review 12 crossings in the capital, saving people crossing an average 29 seconds each time.

TfL’s director of network management Glynn Barton said: “Traffic lights have played a big role on London’s streets for 150 years and our retiming work has already saved 13,000 hours of journey time every day for people using sustainable travel since April.”

 To view an animation depicting how the first traffic light operated here. 

(Photograph: TfL)