Look at this video of Britain right after they won WW2. It's amazing how British society has changed from this into a diversity hell with Africans and Middle Eastern people. Britain today is unrecognizable, so you have to ask: what happened? How could Britain be any worse today if they had lost WW2? You could ask the same question about almost any Western society today.
What I noticed most about the two videos is a real sense of community in the first one, but the second one shows how splintered British society is today. Diversity destroys communities.