Anything that is south of the River Thames is considered "South" (prounounced "Souf" in MLE [1]), no matter the actual distance.

E.g. Waterloo Station would be considered South London but is actually at the same latitude as Buckingham Palace!

Hence why a Londoner would never describe Vauxhall as "Central".

Londoners would generally discount any part of this map south of the river from "Central London":

https://en.wikipedia.org/wiki/Central_London#/media/File:Ope...