I understand, but not sure I can help.

Personally, I have different parameters.

First, the M25. Having escaped it and well in my back, London feels already a good deal "behind me".
Second, the tube. Everything that's beyond the tube doesn't feel very London to me. But that's the perspective of someone without a car and also in Dover direction the tube doesn't go very far anyway ;-)
Third, when I see proper landscape and green. And not parks, but the real thing. That's where the relaxing starts which you mention. Wherever that is on the way to Dover. Maybe a Londoner can help out there^^

I cannot name a place, sorry :-)

Also it might depend which way you leave. I find if you just go straight out of London to Dover, the feeling starts sooner because it's a main road and it's just the way everybody leaves or comes and you head straight to the motorway and it just has this "sense" of leaving, dunno how to put that.

But leaving another way, maybe taking smaller roads, the feeling of the suburbs might be much stronger. I haven't left London south in that way, but driving out north once, the suburbs felt endless because we were zig-zagging on smaller roads.

Oh, I do remember when driving up north towards London, there is a spot where you can have a first look over London from the motorway. That's usually where I feel like "it's beginning, I'm entering the big thing that is London". I never really acknowledged that place the other way round, probably because it's always dark and night when I was leaving.

I checked where Sidcup is and it might work :-) Swanley I remember, and I'd say that's kind of not really London anymore. In my not-very-competent and-very-personal opinion, that is :D Would anybody know where it is, btw? I mean, do you need to drop a name?

I would love to hear answers to your question from Londoners :D
 

Last edited by Whisky (January 27, 2015 12:39 am)

I would say that everything becomes distinctly more rural once you get off the A20 and onto the M20 which is the motorway to Dover. Until then everything is really quite built up. Sidcup is still suburbia. Hope that helps. 

You are welcome. M20 it is!