I came over on a work permit, when the DC office of my company transferred me to London. That was in 1996! And I brought my partner here - on the new UK unmarried partner's visa. But there are lots of Americans here on a work basis - my own university has a London alumni club and meets once or twice a month for drinks in various pubs, and has other events from time to time. I've only been a couple of times, but everyone there it seems is here on a work permit (most often transferred here, as I was, to work for the same employer).