Until recently, the plural elements in our society were, to some extent, glued together by a humanist metanarrative.
That is, the average British citizen shared certain humanistic assumptions with his neighbour, including the assumption that people have certain rights to freedom of expression, but also the responsibility not to harm other people.
It was also believed that life came about by chance and, therefore, people assumed that the material or physical order was more real than any spiritual realm (if such existed at all). All other belief-systems were evaluated in the light of such assumptions.