This lamp was removed from the police station at 277 Upper Street, Islington, N1 upon closing of that station on 7th April 1992.
The text comes from a small brass plaque in the blind window below the lamp.
Site: Blue Lamp (1 memorial)
N1, Tolpuddle Street, 2, Police Station
There is another blue lamp at the old Gerald Road Police Station, much earlier than this one, which is perhaps from the 1930s.