Depends where you go outside of London. In the north I think people are more friendlier as you describe, I think it's not much different in the rest of the south outside of very rural areas (granted haven't lived in the south east so maybe Kent etc is different...I suspect not though!).
I think also in general larger towns/cities tend to have people being less "open" in the way you are describing, whereas smaller towns and villages are more likely to have that - although they will also have parochial quirks on the other side of that coin.