In message ,
Colin Rosenstiel writes

I thought North Woolwich was once South of the river. I.e. the river has
moved over the centuries in this area.

As far as recorded names are concerned, the explanation is quite simple
- North Woolwich was a manor granted to William the Conqueror's henchman
Hamon, Sheriff of Kent, and was thus recorded in the Domesday Book (and
ever since until modern times) as a detached part of Kent.

--
Paul Terry