I've lived in the South for 6 years (having lived in the north for 21). The people who I work with are exactly the same - lovely, friendly, welcoming.
However, it is the attitude of strangers that you totally notice. I live just inside Greater London (so not in the 'too busy to stop' areas on London). I walk through a park at 7:30 in the morning (only in Summer!) and it still depresses me that no one will look you in the eye. I pass 3 people at most during the 5 min walk, so it is nothing like a heaving commute. Not a single person will ever even look at me. I'm not saying that back home I'd be striking up a personal conversation, but you would smile at each other, nod or say 'morning'.
And don't get me started on shopping/town centres. I try to stick to online shopping because it makes me SO angry. I've lost count of the number of times I have said 'NO, THANK YOU', very loudly and sarcastically as the umpteenth person walks through the door that I am holding open for then/waiting on the other side for them to come through first, without them even acknowledging that I exist. Come on people - how difficult is a nod and a smile, you don't even have to say thank you!
And then there's the shopkeeper down the road who is forever on his phone while I'm at the till and just holds his hand out for the money - I try to give him as little business as possible.
So in conclusion, it's all about EYE CONTACT and acknowledging that others exist.
North - Head up, nod/smile/hello/thanks
South - Head down, I don't care about your existence, you have zero significance in my life