Is this a blue pencil I see before me?

A documentary pretends to tell the truth as it really was. A drama documentary pretends to recreate the truth as it really happened. But what does a drama do?

Well, according to John Birt, director-general of the BBC, it just tells lies and creates a new, false truth.

That is why Shakespeare's play Macbeth will not be appearing again on our screens, not if the BBC has anything to do with it.

The shock decision to ban this masterpiece on the grounds of faulty research, political insensitivity and inappropriate attitudes has come like a bolt out of the blue, but the BBC is not budging.

"We have rigorously examined the text of this so-called masterpiece," says Piers Tintagel, newly appointed Chief Text Examiner at Television Centre, "and I'm afraid we have found that it is riddled with so many inaccuracies and misconceptions that we simply can't let it go out as a piece of balanced broadcasting."

Is this because Macbeth is presented as a hero, whereas he is really a villain? Or because he is presented in villainous light whereas we should feel more sympathy for him?

"Nothing like that," says Piers Tintagel, scanning his clipboard. "The fact is that the story as told in the play is nothing like the real facts at all. There was a king of Scotland, yes, but his name was not Macbeth; it was more like Meolbatha. He did not plunge Scotland into civil unrest and bloody battle; he ruled the country well and wisely for something like 18 years. He probably did not murder his predecessor, and if he was turned off the throne, it was probably by people who were more bloodthirsty than he was. We simply couldn't let such a badly researched and misleading drama documentary go out as it is. Current affairs-wise, Shakespeare is a walking disaster area.

"I mean, can you imagine putting out a drama facumentary which portrayed General de Gaulle or Franois Mitterrand as a bloodthirsty monster who arranged for the murder of anyone near or far who seemed to be a threat? The idea is monstrous. It would be tabloid theatre run mad. And yet we solemnly accord to plays like Macbeth the imprimatur of good drama, even thought the facts as depicted are equally far from truth. Why do we do it? Why do we let Shakespeare get away with it? Because it was so long ago? Because everyone in them speaks so nicely, even though these plays twist the known facts so utterly? No, someone has got to take a stand and say: No more of these dramafacumentaroids! Well, that is what we are doing."

But surely it doesn't matter about the original facts being forgotten, if it results in a compelling story and memorable characters?

"You may call this story of unrelieved ambition, power play and immoral vengeance compelling and uplifting if you like. I find it degrading. You may find this portrait of a monster of ravening ambition memorable. I find it about as instructive and uplifting as a portrait of Rupert Murdoch."

Hmm. Well, what are the inappropriate attitudes to which the BBC objects ?

"Oh, where does the list end? Well, the portrayal of mental sickness in the shape of Lady Macbeth is rather unfortunate, as one can't help feeling that we are invited to laugh at her as much as sympathise with her. The whole question of Scottish self-determination is not dealt with in as balanced a manner as one would wish. As far as the supernatural goes, the witches are presented rather as figures of fun ..."

Would he rather that they were taken seriously? Does he think that having three witches around is a necessary part of government?

"Well, if it were left to me I would drop them from the play altogether - either that or introduce a character putting an opposite point of view from that of the witches."

What kind of character would this new person be? A good witch to counterbalance the bad witches? A Lib Dem witch? A Scottish National Party witch? An unelected quango witch ...?

"To be quite frank, the whole play is so ill-balanced on every level that one doesn't know where to start tinkering with it. You mustn't lose sight of the fact that the whole thing is a tissue of ill-natured invention by Shakespeare in the first place. That's why we've banned it."

And what if all the names were changed and the countries were given fictitious names, so that it was set in an imaginary country, not Scotland? And it were a king of a different name?

For the first time in the interview, Piers Tintagel looks taken aback, and turns thoughtful.

"We might consider it then. I'll say no more."