Victorian London - Lighting - Traffic Lights - introduction of 

In the middle of the road, between Bridge-street and Great George-street, Westminster, Messrs. Saxby and Farmer, the well-known railway signalling engineers, have erected a column 20 feet high, with a spacious gas lamp near the top, the design of which is the application of the semaphore signal to the public streets at points where foot passengers have hitherto depended for their protection on the arm and gesticulations of a policeman - often a very inadequate defence against accident. 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

Punch, March 20, 1869