HERE'S a question to get things rolling: Is the BBC a left-wing plot aimed at undermining society?

Occasionally, a letter will arrive at this and other newspapers making such a complaint.

Often they are written in green ink, a colour chosen by those whose anger is leading them towards the edge.

I have never seen a letter written by Paul Dacre, the editor of the Daily Mail, but I like to think he would favour this hue of ink.

Last week, Mr Dacre made an astonishing attack on the BBC. Normally heard but rarely seen, he stepped from behind the pages of his newspaper to deliver the Hugh Cudlipp lecture.

He was not, from the text of his speech, a happy man.

It seems common for newspaper editors to dislike the BBC. Mr Dacre takes it to new heights. In his lecture, he accused the corporation of "a kind of cultural Marxism" that harmed political debate and failed to represent the views of millions of licence fee payers.

He said the BBC tended to left-leaning views, and was part of what he called the "subsidariat" of newspapers and broadcasters which did not pay their own way.

"BBC journalism is reflected through a left-wing prism that affects everything - the choice of stories, the way they are angled, the choice of interviews, the interviewees and, most pertinently, the way those interviewees are treated," Mr Dacre said.

Mr Dacre said he admired much of what the BBC did, but was disturbed by the way the corporation was "in every corpus of its corporate body" against "conservatism with a small c'."

He also averred that the BBC, along with other members of the "subsidariat", was consumed with political correctness and that "a self-appointed elite" was imposing "minority views on the great majority".

A puzzled person might, at this juncture, pause to wonder if this was the same Paul Dacre who edits a newspaper with a very particular and peculiar view of the world, a paper which views life through a cracked right-wing prism, which instils fear with its constant scare stories, and is never happier than when lecturing women and warning its readers about what an evil, brutish place modern Britain has become.

Now it is true that my politics come from the different end of the shelf to Mr Dacre's, but I am still puzzled by his theory. I glanced again at the Radio Times, half expecting to find a popular series called Strictly Come Stalin, perhaps, or a drama entitled Doctor Who Goes There, Comrade. But no, everything looked normal.

His argument is perplexing. Would a "left-leaning" institution give such fawning coverage to the Royal Family? Would it treat religion with so much reverence, still giving a prime time slot to Songs Of Praise, or allow the Today programme to be interrupted by the religious ramblings of Thought For The Day? Would it give such constant and numbing coverage to business stories in all of its news programmes?

In truth, the BBC more or less upholds traditional values and, if anything, tends to the trivial in its mainstream TV news, especially with all those gimmicky graphics appearing all over the place.

In any debate on the future of the BBC, it is worth asking a simple question: Where would we be without it?

We would, I have to say, be much worse off. The BBC is far from perfect, but it is a cornerstone of national life.

It is true that the licence fee remains an anachronism, but the alternatives - yet more adverts interrupting programmes, intrusive sponsorships, threadbare public service broadcasting - make this "viewer tax" a bargain.

There are many sources of news, comment and entertainment in this country, with room for Mr Dacre's Mail and the BBC to rub along.

And if, as happens with this columnist, the Daily Mail sends your blood pressure through the roof, you can always pick up something else to read.