Matthew Norman: Only a written constitution will do

In the constitutional context, 'unwritten' is the euphamism for 'non-existent'

The hot air that gusted over two pages of yesterday's Independent by the main party leaders could have powered a Zeppelin from Parliament Square to New Zealand. They still don't get it, do they? Not really. Even now, after seeing and hearing the evil at close quarters for years, they are content to speak vacuous waffle.

Which of the three articles was most disappointing is a more intriguing point of debate than their content, but Gordon Brown's was certainly the saddest. Close parsing of his text offers too agonising a glimpse of a man screwing his eyes tight shut to avoid his own reflection, so I'll keep it brief.

The man who fought like a tiger to keep expenses hidden and perpetuate the scandal informed us that he "will not tolerate behaviour that is against everything I believe in." Mm. "In my first Commons statement as PM," he went on, " I said that Britain needed big changes in our constitution so that the British people held greater power..." Yes, Gordon, and then you did what?

Before moving next door, he did make noises about an entity denied a mention in any of yesterday's offerings. "Gordon Brown may introduce a modern written constitution... in an attempt to rebuild voters' trust in politics," ran one report in January 2006. Another in May 2007 revealed that "Gordon Brown will try to restore public trust in British politics by proposing an all-party convention that could pave the way for a written constitution."

Amnesia struck the second he took over, of course, as it did Mr Blair when his vast majority drove a manifesto promise of a referendum on electoral change from his mind. How else could it be? You don't spend every waking moment dreaming of and scheming toward the closest thing to unfettered power known throughout the democratic world to give gigantic chunks of it away.

Which brings us to David Cameron. He's had a fine time playing the matador, not surprisingly since Gordon has the constitutional insight of an ox. His footwork has been dazzling, but this article was a mis-step. Much as I admire his dextrous way of pressing the erogenous buttons – radical decentralization of power; end to sofa government; return to Cabinet government; all the usual suspects – there wasn't a hint of future penetration.

It would have been naïve to expect more than flaccid foreplay, because by background and nature Mr Cameron couldn't be less suited to driving change. He reads, between the lines, as he is – an old school, One Nation, don't-scare-the-horses, status quo Tory. "We also need to look seriously at the case for fixed-term governments," he says. And having done so, he leaves unsaid but crystal clear, we'll quietly decide against. Never has Mr Cameron's heir-to-Blair ambition been better illustrated, and seldom has he looked so weak and shifty.

As for Nick Clegg, his wish list came so close to my own that it read like an old column, thankfully precised. But wish lists be damned. This is the moment for bullet points – sharp, precise, specific, unequivocal – and the first of them should promise the written constitution he weirdly failed to mention.

"We must restore democracy by giving power back to the people," he wrote, and again you thought, well, what does that Wolfie Smith slogan mean? By what mechanism do you propose that such a restoration could be made, and enshrined in such a way that it couldn't be unmade?

Irritating as Mr Clegg's windiness was, at least he is palpably sincere about reform (of course he is; the Liberal Democrats have so much to gain) where Messrs Brown and Cameron clearly are not. They are the ex-smokers of devolved power, boring the room to death with accounts of how much better they feel, and how they've started noticing the stale smell on those yet to see the light, but they're secretly gagging for a drag. The minute the missus leaves the room, they'll cadge a crafty puff, and before you know it they'll be back on 30 a day.

The reason writing everything down is the only way to keep them honest is that it's the only way to remove the lure of dishonesty. In a constitutitonal context, "unwritten" is the equivalent of "gentle", as in "the gentle comedy of Roy Clarke." It's a euphemism for "non-existent". The reliance on a perplexingly series of ignorable precedents, and conventions so elastic that they can stretched into other shapes at will, is what enabled the political system to atrophy like this in the first place.

If you seriously wish to reconfigure the power balance between electors, executive, legislature and judiciary, you have to put the mechanics on paper and place their protection at the heart of the democracy. "We the People" seems a useful starting point,because the American version has stood the test of time astoundingly well. More than 300 years later, that constitution infuses US democracy with a vibrancy at which we can only stare in anguished wonderment.Every politician sent to Washington swears or affirms allegiance to it. In a sense it is America's sovereign.

Admittedly it was written by an outlandish coalescence of political geniuses, and we're a little light on Jeffersons, Adamses and Hamiltons at the minute. But it's there as guiding light, and much of what we need (from the bill of rights to the two term limitation on the head of government) lies in the amendments alone.

I haven't heard a single coherent argument as to why we shouldn't have one of our own, not to mention a long national debate about its contents to counteract the sclerotic apathy that has let us drift to this pass.

Mr Brown once feigned a commitment but forgot it, while Mr Cameron was never keen and apparently never will be. This issue has always belonged to the Lib Dems, because no one else was interested. If he believes in it, as he has said before, Mr Clegg needs to sell a written constitution as the only viable route to fundamental and enduring change. If he can't manage that, and quickly, he should do the decent thing, stand aside, and let Vince Cable have a crack instead.