"Fairness, impartiality and objectivity are the essence of public service broadcast journalism. This understanding is enshrined in the BBC's charter and provides a key justification for the licence fee.

Now, however, an explosive insider's account threatens to blow this cosy assumption clean out of the water as a fraud upon the public. Robin Aitken, who spent his entire career as a BBC journalist, has written a book accusing the BBC of institutionalised leftism.

This is by no means the first time such an accusation has been levelled, but generally such critics have been dismissed as parti-pris. This is why Aitken's book, "Taking Sides: Bias at the BBC", is so significant.

For 25 years he chalked up solid experience across the board as a BBC reporter, covering some of the biggest stories of the day. In other words, he is BBC man through and through. So when someone like this lifts the lid on newsroom culture, it carries weight. And his message is that BBC journalism is as bent as a corkscrew."