Leading article: The BBC still does not understand

It is no surprise that the BBC Trust has acted quite so feebly in its report on the Russell Brand and Jonathan Ross prank. A general castigation but no specific punishment is what you might expect from an oversight board that has been set up to combine the contradictory tasks of defending the BBC to the outside world and acting as its policeman internally. But it is a response that fails on both counts. It will do nothing for the corporation's standing outside and nothing to shake up its management within.

The story of Brand and Ross's ill-judged jape is now so well known as to hardly bear repeating. In so far as the BBC Trust's investigation has produced anything new, it is the picture of a management that, while concerned at the swearing, showed no sensitivity towards the issue of taste. But then that is the true measure of the failure not just of the entertainers' line managers – two of whom have since resigned – but a far more dangerous failure of the trust to understand how the corporation now looks to the public. Whatever the rights and wrongs of this particular incident, the reality is that it has proved perfect ammunition for the BBC's enemies, which are influential and growing.

At the best of times the BBC has its critics, and not only among commercial rivals furious at the advantages and government financing it enjoys. And these are no longer the best of times. The licence fee, at £139.50, is at the very limit of what it is politically tolerable, and to some MPs, well beyond it. Constrained by the licence fee ceiling, the corporation has sought to keep growing by expanding its commercial arms and delving into every area of digital communication. To its management this is logical. To its enemies it is overweening. While for its own good it is making the institution too large for good governance, as this latest case has shown.

So far the majority of the country has retained a natural affection for the BBC as a peculiarly British institution. But the corporation's leaders can no longer take that loyalty for granted. Now that television can be seen online, the licence fee has become less enforceable and less justifiable. A younger viewership brought up on a multiplicity of entertainment channels does not feel the same particular affection for the BBC and what it represents. The middle classes who do also feel quite strongly that its special role brings with it a duty to uphold standards of behaviour as well as language.

No other country has a broadcaster as trusted and as admired as the BBC, but then no other country imposes so high a tax to sustain its public broadcasting service, if it imposes a tax at all. It may well be unsustainable over the long- or even medium-term future. If only the BBC and its trust understood that. On the present evidence, neither the director-general Mark Thompson and his senior management, nor Sir Michael Lyons and his trust, show any sign of it.