Here is where I confess that I still have trouble telling them apart. :P Somebody else will have to make the quiz for me so I can find out.

But if we limit it to downstream from Teddington Lock, probably Beverly Brook anyway, given my deep and lifelong interest in things like riffle-pool sequences and urban green spaces and permeable concrete.

Upstream ... dunno, but some of the Father Thames' folks remind me rather a lot of my actual RL relatives, so I'm not sure if I want to think about that one very hard. (I had a direct paternal ancestor who ran off to be a carnie as best we can tell.)

Which are you? :D