well what does work? People marry for love all the time and don't care about "class" and marriages fail.I think exactly the opposite. The class system in the UK is becoming less and less structured and the days of the bon ton and the hoi polloi are long gone. Its been proven time and time again that marriage for status and titles and keeping a bloodline pure doesn't work in modern times.
The day laborer.
I don't think that the class system has gone, it never will and while there is greater class mobility, that hardly guarantees successful marriages. Carl Gustaf of Sweden married a middle class girl for love, as far as I know he has been playing around and it isn't a case of being with one woman he loved, its been a lot of them.
I am sure the Middetons pushed to an extent, and I'm sure that they would not be too happy if their kids had (after all the wrok they did to make a fortune an send them to expensive schools) married well below themselves in terms of class and money.