Wouldn't that posit that a large part of the UK population suddenly decided to let itself go in the last ten years, for no apparent reason? It would also seem to suggest that in the 1930's everyone in the UK and US did the same, only to pull themselves together in time for world war 2.Or is an increase in poverty a cause of people making themselves unemployable because of persistent criminal behaviour? It can be both cause and effect.
I'm not trying to straw man you, honestly, it just seems an odd argument.
I've heard it suggested that poverty of itself doesn't cause violence, but inequality does.