It is a bit rich for David Cameron to express concern about social justice and inequality when as a loyal lieutenant of Michael Howard and Norman Lamont he was personally involved in economic policy that made the problem worse.
That's (a bit) rich!
something that you say when someone criticizes you to show that you do not think they are being fair because they are as bad as you. I'm greedy? That's a bit rich, coming from you! You ate all of the food in the fridge!