NO BBC person gives a speech without mentioning public service at least a dozen times. At a conference last week, the director of policy, Patricia Hodgson, didn't entitle her address "The BBC in the Digital Age" but "Public Service Broadcasting in the Digital Age".

Yet an accumulation of incidents is beginning to make me wonder whether the public service ethos of the BBC is less pervasive than it appears. For example there is the recent decision to move daily coverage of Parliament into what Gerald Kaufman has aptly called "the ghetto of long wave radio".

According to a leaked report, an edition of The Rantzen Report is due to be criticised later this week by the Broadcasting Standards Commission as "inaccurate, misleading and unfair". And now we are arguing about whether fly-on-the-wall documentaries are sometimes faked. As far as the BBC's The Driving School is concerned, a spokesman said: "Some of it was faked. It was a light-hearted documentary. But the integrity was still there". Is this possible: fake and integrity in the same product?

Of all the many things which comprise public service broadcasting, reporting Parliament is not the least important, particularly as newspapers, regrettably, have substantially reduced their coverage. Is Yesterday in Parliament intrinsically dull? I don't think it is, though doubtless an inspired editor could still improve it. The raw material is more than adequate for the making a good programme.

So far as criticism of The Rantzen Report's allegations about a hospital are concerned, I am less bothered about the rights and wrongs of the case than I am about the BBC's own investigation into complaints about the programme. The Complaints Unit found "minor inaccuracies" and "clear unfairness". None-the-less, no apology was made. As a result, if the Broadcasting Standards Commission does indeed make trenchant criticisms, we shall be left wondering whether the BBC's internal inquiries are more concerned with shielding the corporation than rectifying errors.

However I think that the BBC's stars, seeing a steady trickle of such incidents, take aim at the wrong target. The other day Kate Adie, like many others, put the blame on management style. She says that the BBC has developed a huge division between the people who run the corporation and those who make the programmes. She went on: "It has become more acute in the past decade at the BBC because there is undoubtedly now a management which is a reflection of modern business methods." Certainly there is a curious management-speak, of which Ms Adie says she is ashamed. I saw a BBC recruitment advertisement recently which referred to all 500 qualified accounting staff as being "members of the Finance family".

The fact is that the division which Kate Adie describes exists in most institutions. There is always a gulf of understanding and temperament between the creators of a product and those concerned with administration. The Royal Opera House has provided eloquent evidence of this fissure. Probably, to take a completely different example, the people designing aircraft engines at Rolls-Royce feel similarly frustrated. It is an inevitable tension which is by no means always damaging.

Of course the BBC very well understands the public interest. A paper, "The BBC's Ten year Vision", predicts that the burgeoning commercial sector will increasingly gravitate towards a narrow range of programmes, favouring light entertainment, long-running serials, sport and niche services, despite having a greater number of channels. In contrast, the paper argues, the job of the public service broadcaster in these circumstances is to serve the whole audience, not just those parts which are commercially attractive, to make programmes which the market will never provide and, by setting standards and taking risks, limit any tendency among commercial broadcasters to focus on the lowest common denominator. In other words, the BBC is to be the sheet anchor of the broadcasting system.

That is all very well. But it is not the only matter weighing on the corporate mind. From the outside, the BBC appears as the most fortunately placed corporation in the country. It knows exactly what its revenue will be this year, next year and the year afterwards. Whether it performs badly or not, the licence fee will continue to roll in. Added to which, it has dominating shares of most of its markets. By contrast, Rupert Murdoch's operation looks as dangerous as trying to fly non-stop round the world by balloon. But that is not how the future is seen within the citadel. The BBC's nightmare is that one day it might lose the licence fee or see its value drastically reduced. As it is, the BBC can see that the licence fee is unlikely to grow as quickly as its rivals' advertising revenues or the fees from subscription and pay-TV. That is why the corporation has to hack away at its cost structure, and the result is that Ms Adie feels herself dominated by management types.

As it celebrates its 75th anniversary, the Corporation feels itself on the retreat. For its first 50 years it maintained its market shares at 100 per cent. Then in the 1950s, it lost its television monopoly, in the 1970s competitors came into local radio and finally in the 1990s the monopoly of national radio went. As a result, considerations of public service are not always, or even generally, the main focus.

The BBC is just as concerned as any commercial broadcaster with attracting the largest possible audience. It does not see how it can continue to justify the licence fee without providing popular services which most people want to watch. If the market generally is dumbing down, then the BBC will dumb down. If the most entertaining fly-on-the-wall documentaries require a little contriving or a bit of cheating, then that is what will be done. If parliamentary news appears boring, then it can no longer be allowed to occupy a prominent position.

The corporation then, is subject to two commandments which are often in competition with each other - secure the public interest, and keep up the numbers. This is where the dangerous tension lies, rather than between managers and creative people. Actually the numbers are looking good. In spite of cable and satellite, BBC television's share of all viewing has held steady at around 42 per cent to 43 per cent.

This is the task for the governors. In the annual report, these distinguished people outline a range of duties which they have assumed. To me, their job is simply described. It is to arbitrate between management's understandable desire to retain high market shares in the various broadcasting markets the BBC serves and the requirements of public service, relatively unpopular as these may sometimes be. Chris Smith, the Secretary of State for Culture, has quickly grasped the danger. He said last month that he wanted to establish formal meetings with the governors at least twice a year so that he could ensure that the corporation was sticking to the terms of its Royal Charter. "If it is forgetting that it is a public service broadcaster, then it is forgetting its raison d'etre," he said. Exactly.