Illustration: David Foldvari

When the Conservatives' deputy chairman, Lord Ashcroft, revealed that his party donations are dwarfed by the sums he's withholding from the nation by tax avoidance, the Tories didn't panic. They decided the crisis didn't require large-scale political fire-fighting – a little squirt would do. But George Osborne's terribly busy these days so they plumped for Michael Gove.

I doubt he was thrilled. Ashcroft is what an old-school Tory might describe as "the sort of chap who wants to run the club but won't pay his subs", the club in this case being Britain. It's a difficult position to defend and interesting that Ashcroft didn't try himself. Maybe he kept saying: "Shut up or I'll buy you!" when he practised TV interviews. That doesn't go down as well on Channel 4 News as it does when booking a table at a busy Belizean restaurant.

Gove did a decent job fielding Jon Snow's questions and then beetled over to the BBC to face Newsnight's Kirsty Wark. Gove's tactic was to keep repeating that the other main parties were bankrolled by men with equally poor senses of civic duty and ignore Wark's point that Ashcroft's role as deputy chairman made his case different. Then, at the end, Gove went on to the attack.

"We'll be watching, Kirsty," he said darkly (although it's not as if he ever sounds like Bagpuss) and then, in a significant tone: "The broader question will be, 'Is the BBC failing in its duty to hold other parties to account?'", leaving Wark to wrap up the interview in a fluster ill-concealed by a pretence of being hurried. Maybe she had the director general screaming in her earpiece: "Tell him we'll get rid of CBeebies if he'll just leave us alone!"

How should Gove's remarks be interpreted? The cheap tricks of a deft debater? The usual politician's paranoia about BBC bias? Maybe it's my own paranoia but I thought he meant: "We're not going to have to take much more of this shit. There are going to be some changes round here."

The next morning, as Mark Thompson announced his plan to close a couple of radio stations, slim down the website, spend less on imported programmes and sport and generally get his tanks off the Murdochs' lawn, and reseed it, he insisted in the Guardian: "The proposed changes are not a piece of politics." Smashing! That means they can't be. If politics were involved, he'd have to say so, wouldn't he? There's probably some sort of law, like with salt in ready meals. But who can blame him for addressing political realities when the Tories are sharpening their knives live on Newsnight?

Over the last two years, as recession and internet have obliterated their profits, the BBC's competitors have conspired to make headlines out of its failings. Not even Katie Price's insatiable thirst for publicity can elicit as much press as the corporation gets while trying to keep a low profile. Every night, it's metaphorically falling out of some nightclub, inadvertently showing its muff.

And the politicians have joined in, as if they genuinely believe this torrent of negative coverage is an expression of public concern rather than corporate envy. This, in turn, forces the director general to court the politicians. Not that he can ever win, as Ed Vaizey, the shadow culture minister demonstrated. When it was first leaked that 6 Music may close, he welcomed it; three days and a Twitter storm later, he said he'd become "an avid listener". What would Thompson have had to jettison to keep him onside for a whole week?

The BBC exists in a nest of paradoxes. First, it's supposed to be impartial yet accountable – impartial politically, but accountable to the licence fee payer. But how is that accountability to manifest itself other than through politicians whom its impartiality should empower it to ignore? Getting people to text in their snow pictures seems to be the current best guess.

Second, it's supposed to provide content that the free market wouldn't otherwise support and not hamper commercial competitors too much, and yet remain popular enough to prevent viewers resenting the licence fee. People, including Thompson last Tuesday, say the BBC should "concentrate on what it does best", but most of us wouldn't pay £142.50 a year just for the Proms and Storyville. We also want Strictly Come Dancing, Football Focus and, in millions of cases, Jonathan Ross.

And third, the licence fee is unfair. It's basically a poll tax (maybe that's why Mrs Thatcher kept it). It would be much fairer to fund the BBC from income tax. But that would destroy its independence and leave its future in jeopardy at every budget. That's why I firmly believe that the licence fee is the only workable system, a fudge though it undoubtedly is.

These contradictions make it very easy to find fault with the BBC and let its critics evade the real question which is, simply: do we want it or not? It's a binary choice, all or nothing. I once came across a very persuasive analysis of organisations (it's from the book Intelligent Leadership by Alistair Mant) which divides them into two categories: bicycles and frogs.

A bicycle is put together from interchangeable parts. You can take a bicycle-like system apart, polish or improve elements and then reassemble it into something that works better. A frog, however, evolved as a whole. If you chop a little bit off, it'll muddle along. And another little bit and another and it'll still be a frog, albeit a less functional one. But finally, with one tiny further change, it will cease to be a frog and nothing you can do will ever put it back together. Well, the BBC is an organisation to melt Miss Piggy's heart.

Its anatomy isn't perfect, as I've discovered while making The Bubble, a BBC news-based panel show with which BBC News has refused to co-operate. But sometimes a frog kicks itself in the head, I suppose – or to characterise BBC News's decision in a way to better reflect how they see themselves in relation to comedy, head-butts itself in the rectum.

I understand why the BBC frustrates the private sector – it makes business much harder for them. But I don't know why they expect the public to care, other than out of concern for the Murdoch and Rothermere families' finances. In all their whingeing, they've consistently failed to point to any other country where, thanks to the unfettered function of a free market, better television, radio and online content are available.

On the contrary, the BBC is the envy of the world. Why are we letting its competitors, and the politicians they have frightened or bought, tell us that we can't keep it as it is?