This splendid object is over the road from the entrance to Postman’s Park in St Martin’s le Grand.
It’s a reminder of a time when the police didn’t have radios and the public didn’t have mobile phones (or, for most people, telephones in their houses).
The red light at the top would be illuminated when the station wanted the officer on the beat to call in for instructions. The ‘phone would be in the top compartment of the box and a first-aid kit was in the space below.
There are, apparently, eight such “call posts” still in the City of London, and several more scattered around central London (including one at Piccadilly Circus), although none of them are operational. Those for the City of London Police are painted light blue and those for the Metropolitan Police are dark blue – even when it comes to street furniture, the City and the Met need to keep their fine distinctions.