Being live in junction between Gloucester Road and Comwell Road for 3years, I have lost my curosity towards siren of both Ambulence and Police Force. The reason is, about 20 sirens pass through these two roads everyday! I do not live beside any hospital or police station, therefore it is roughly homogenous and can be assume to happen in other places of London without lost of generality.

Why do they always use siren? For returning home asap? I do not have a clue…