I tell people I live in Forest Hill, if they need more explanation I tell them it is the centre of the universe and feign ignorance about where they live (and then often refer to their neighbourhood as on the way to the M1 - before demonstrating that I'm actually quite familiar with their area). I'm no longer prepared to accept that North Londoners are allowed to be ignorant about South London.
I'm a bit more generous to people from outside London, but they are always happy with the explanation of London or South London - they don't need to know more than that. It is only people from North London who require three points of reference for anything beyond the tube system and still don't understand.
I live in Forest Hill. You got a problem with that?