Ironically, the on-the-Hill bit of this town (actually a different town) always floods around here (it's not very posh though), cue gripes to the council about drainage, but the main culprit seems to be expanses of paving that channel water into the storm drains, and new developments which take this model as the default.
Walking through Kent, as one does, it's shocking the number of new developments – there are several huge ones metastasizing from the eastern edge of Tunbridge Wells and, well, everywhere else. I don't think you can walk through a town without seeing posters to campaign against some development (and they're often not small, there's one for >4000 homes in Capel/Tudeley). Even in Surrey, the local council has been niggling over a 'garden village' which seems to be a field full of houses with no local services.
I'm not sure where all the people are coming from to fill these houses.