Walking around Primrose Hill in the former borough of St Pancras I came across this lovely example of a renamed street which naturally made me ask why would you do that?

This fascinating article about fireman Fred Rayment explains all: essentially London County Council found itself with too many streets with the same name so decided to rename them.

Chalcot Road/St George's Road

ETA: Actually, there is a bit more to the name changing than the London County Council which you can read about here.