The class system in Britain has always been much more nuanced than simply upper, middle and lower. The middle was – and, for those who care, probably still is – divided into upper middle, middle middle and lower middle. The upper classes have always regarded "old money" as socially superior to "new". Nouveau riche, of course, is different again. Money, however, was never the main criterion for how the British class system worked and people can be upper class or aristocratic and stony broke at the same time. Trade is another issue – George Osborne, for example, will never be fully accepted by the traditional upper classes because his money comes from wallpaper and paint. Class in Britain is an esoteric business and there are all sorts of subtle differences between Scotland and England.
Incidentally, observing that there is still a top and a bottom class doesn't require a PhD in sociology.