Is political correctness a myth?

I hear more and more often that political correctness is mythical, a straw man created by right-wing ideologues so they can launch tirades against the humanitiarian policies of the Labour and Liberal Democrat parties.

I just downloaded the 'Electoral Commission Guidance on registering as a political party'. Government document from a government department. On the cover are five pictures montaged. The first one is of a young woman who looks Iranian or perhaps arabic. The second is a stock shot of the clock tower at the Houses of Parliament. The third is of a hand holding a mobile phone. The fourth is a middle aged black woman. And the fifth is a hand putting a letter in the letter box.

As a piece of propaganda, its dull and worthy, but it is undoubtedly politically correct. Only 6% of the British population are anything other than white anglo-saxon yet you would think from this document that there weren't actually any white people in the country at all. Thats just silly and condescending and factually incorrect. Which is a pretty good working definition of political correctness.