From soap operas through crime dramas to single-episode plays, the BBC has a cast of baddies — its version of Richard Nixon's enemies' list:  Lady Thatcher, conservatives, people worried about immigration or multiculturalism, businessmen, traditionalist schoolteachers, army officers, toffs, eurosceptics, evangelical Christians, Catholics and Zionists. I doubt Sewell will accept this from me, but the dramas that follow are not truly left-wing. They are rarely concerned with the redistribution of wealth and power. Rather, the BBC allows the liberal wing of the upper-middle class in the culture industries to indulge its hatred of the conservative wing of the upper-middle class in the City, government and armed forces.

The result is moralising, formulaic drama whose characters are as predictable as the heroes and villains of Victorian sentimental fiction or socialist realism. Plots run like trains down a track. The good are vindicated and the wicked exposed. As soon as you heard, for instance, that the BBC had commissioned Sir David Hare to write on the war on terror, you knew before it began that the Americans would be vicious, the British establishment would be their poodles, and Jews would be conspiring to murder the innocent. That is the way the  political drama must be. The BBC would never have commissioned a British version of Homeland because its American writers acknowledged that radical Islam was a psychopathic force in the world that the US had to fight.

No drama executive has issued a directive banning similar storylines here because explicit prohibitions are not the British way. Everyone knows the rules of the game. If they needed them spelt out, they would not have been allowed to play in the first place. Someone once described the British establishment as a committee that never meets. The BBC is a censor who never speaks.

Sewell remains a corporation man at heart. Rather than allow liberty to flourish, he wants the corporation to balance left-wing plays with right-wing plays.  He sounds like colleagues of mine who hate the right-wing propaganda of the Daily Mail, not because it is propaganda, but because it is right-wing. If editors could produce a left-wing Mail, they would see nothing wrong with it. They do not understand that in journalism as in drama, the important task is not to match left-wing agitprop with right-wing agitprop, but to fight agitprop in whatever form it comes.

 The BBC has failed to compete with the best television because its suffocating conformism, its woozy moralism, its prissy language and petty prohibitions are the enemies of creativity. Writers and directors need freedom from its soft censorship, not to have new chains replace old manacles. If they were freed, who knows? Perhaps we would see members of ethnic minorities who were not always victims. Or left-wing social workers who were not always virtuous. Or businessmen who were not always crooks. I am sure we would see more leftish sentiments on screen, but that should not be grounds for conservative complaint.

Theodor Adorno said of 1940s Hollywood, "A film which followed the code of the Hays Office to the strictest letter might succeed in being a great work of art, but not in a world in which a Hays Office exists." The same applies to British television. A left-wing writer might yet produce a great television drama. But if, and only if, the BBC did not dictate its politics in advance.