Having lived in the area for over 30 years and done a lot of driving in the time, I have to say that FH is no worse than most other parts of London I have driven in.
I am surprised as its not usually anywhere near as bad as this, certainly not on a regular basis. The thing to remember is a lot of cars driving IN Forest Hill are probably not FROM the area, merely passing through.
Police, PCSO's, traffic units, I see plenty on a regular basis in the area, a lot of operations are based from my road. But typically the 'not one around when you need one' rule applies from time to time.
As for Manor Mount, I know it well and yes I agree, historically blighted by idiot drivers.