Although I live in East London whose inhabitants are, on average, significantly less well off than other parts of London, the road I live in is quite a nice one and, judging by the amount of home improvements going on, a relatively well off one. However, during the last election campaign there were several Labour posters displayed on it.
Just because someone is fairly comfortable, doesn't mean they won't vote Labour. Conversely, just because a person is quite poor doesn't mean they will vote Labour. In London, and especially in less wealthy areas, it is inevitable that you will be living fairly near "poor people" - and a variety of different nationalities. Those who aren't happy about that - like a Conservative friend of mine who has decamped to Essex - usually move further out as soon as they are able. I, and many of my other friends - mostly Lib Dems, Greens and Labour, but including a few Conservatives - have lived here for 30 years or more. Just because you have a couple of Lib Dem friends with delusions of grandeur doesn't mean that they are representative of Lib Dems - or indeed anybody but themselves.