http://I have always found the few Americans I have met to be the type I wouldn't have wanted as friends in America. The Brits are so much more down to earth and realistic about things. It is also nice to not have to deal with the super egos that you find in the states. I didn't make a lot of British friends until I had my son and started go to parent and toddler groups.
I have lived here for almost five years now and absolutely dread going back to the states, even for a short visit. However, when I first moved here I couldn't stand it and wanted to go home everyday. Now I would never move back there.
It probably does have a lot to do with the individual, and possibly the location. Not just where you live in the UK, but where you've lived in the US as well.
When I was going through elementary school, I moved a lot and had to make friends fairly quickly. Its easy to have casual friends and acquaintences, much harder to develop a very close friendship with someone. I had some very close friendships back home in AZ, but when I moved to Utah, I found that although I knew a lot of people, there were few I could consider a real friend. I did make some, but they were mostly people who had come from other states, since the general feel for Utahns is "insular". My Fiance has been to most places in the States, from the upper northeast clear down to Florida, and from the Pacific Northwest through California and the Southwest, and he has said Utah was the least friendly of all the places he has visited.
I've lived here for 10 years and still don't feel like I have anyone I can call a true friend. I've lived in the town I'm in now for 2 and a half, and don't really even "know" anyone I could maybe turn to in a time of crisis. I'm very much on my own most of the time. If I lived on the East coast, I'm sure I'd have several friends which it would be very easy to be close with. I have a tendency to get along with people from there a lot more easily than with people out here. I went to a 5-day training in Oregon last month and got on immediately with another woman there from DC. We still talk regularly on IMs. More often than I do with my old friends from AZ!
My fiance has said that he's sure I'll have no trouble making friends there, but I saw this post and immediately started worrying. If people over there are as insular as they are here, I will have some trouble. But then I remembered an incident when I was visitiing in April where I had a very fun conversation for about 30 minutes with the girl behind the counter in a chocolate shop while he stood uncomfortably by the door. I do have a tendency to talk to stragers. Is that a bad thing over there? We'll be living very close to London, and I'll most likely be working in the city. Is it easier to make friends there?