In the world’s first traffic lights, green meant slow down and prepare to stop
There was only stop and caution

The world’s first traffic lights were installed in 1868 to allow politicians to safely cross the busy road to enter Parliament.

The Westminster street semaphore, from the Illustrated Times, 16 January 1869. Copyright the British Library Board via the British Newspaper Archive.

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In the months before its installation, two MPs had been badly injured and a traffic policeman killed at this very spot.

The lights took the form of a set of semaphore arms 20 feet tall (approx 6 meters) for daytime use and green and red gas lamps for night-time use.

The only settings were “Stop” and “Caution”.

At night, green meant effectively slow down and prepare to stop.

The Engineer magazine described the unveiling of the “handsome semaphore signal post” as having been “uncovered after the manner of an inaugurated statue”

The device was manually operated by a policeman.

Information about the new system. The signals were caution and stop only. At night, substitute red for stop and green for caution

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The lamp will usually present to view a green light, which will serve to foot passengers by way of caution, and at the same time remind drivers of vehicles and equestrians that they ought at this point to slacken their speed. The effect of substituting the red light for the green one and raising the arms of the semaphore – a simultaneous operation – will be to arrest the traffic on each side.

– The Express, 8th December 1868


The new system seemed to work quite well.

‘The regular town drivers are fairly, and to quite an unexpected extent, amenable to the signals,’ the Illustrated Times granted.

Cabbies naturally weren’t happy.

 One commentator, on approaching the ‘Dreadful Portent’ from Westminster Bridge, asked his driver what it was.

‘Another o’ them fakements put up to wex the poor cabbies,’ came the reply.

The satirical magazine Punch shows this ‘Dreadful Portent’, glowing in the fog.

Punch’s terrific apparition

First Traffic Lights had a strange whiff

While a policeman was still required to operate it, but raising and lowering of the arms could be carried out “without any strain or effort”.

Even “a lady or youth” could do it.


A report published in The Times on 6 January 1869 noted that the “roadway round the pillar has smelt of gas almost from the time the pillar was put up, as if it was soaked with gas”.

One night, the constable on duty – unaware that gas had been slowly leaking into the pillar’s hollow column – opened the box.

The flame at the top ignited the gas, which exploded, killing him.

The first traffic lights were taken down and the idea was shelved until 1929.

By a strange quirk of fate, the first vehicle-actuated signals in Britain (on the junction between Gracechurch Street and Cornhill on the City) were also destroyed by a gas explosion in 1932.

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