Welfare Reform and Work Bill

I was interested to hear the Secretary of State talk about the benefits cap and fairness. Is he aware that his right hon. Friend the Member for Epsom and Ewell (Chris Grayling) also talked about fairness and the benefits cap, saying that it was only fair that people’s benefits were capped at the level of the average that someone would expect to earn by working? At that point, the cap was £26,000; now, it seems that average earnings are £23,000 and £20,000. What is the reason for the difference?