Britain has become ever more diverse in the past few decades. But is this a threat or an advantage? “When solidarity and diversity pull against each other, which side should public policy favour? Diversity can increasingly look after itself – the underlying drift of social and economic development favours it. Solidarity, on the other hand, thrives at times of adversity, hence its high point just after the second world war and its steady decline ever since as affluence, mobility, value diversity and (in some areas) immigration have loosened the ties of a common culture.”