Why does Cameron stand by someone accused of using figures "likely to mislead he public"

It is unsurprising that the Tory press and media have tried not to mention Chris Graylings rather disturbing misuse of statistics in order to make a political attack on the government.

This government is poor enough to be criticised on its real record. Quite why Chris Grayling has to go to such lengths to make inconsistent comparisons between data is really poor, highlights his unsuitablility for high office and must make people question why it is that David Cameron is standing by him.

Are front bench spokesmen for the Tories encouraged to lie ?

Anyway, the Independent has a full listing of Grayling's gaffes for people to check out.

Update Although it is a shame that the Independent do not know that the headline "Lies damn (sic) Lies and Tory statistics" should really read "damn(ed)", from the Mark Twain/Benjamin Disraeli quote. I recall the Labour Party using the incorrect quote in a leaflet they put out to slag of the Lib Dems in 1997 saying our bar chart statistics were wrong. Actually they turned out to be only one half of one percent out from the final result.