He'll have been groomed to look good on camera and taught always to say the right (ie popular) thing by a team of media advisers.

He'll be adept at rehearsed spontaneity and contrived authenticity and he'll have been elected on an inoffensive centre-ground manifesto which offers tax breaks to "hard-working families".

Yet, at the same time, he will be promising to boost public services and eliminate poverty. He will boast about his unshakeable vision, but it will really be the latest opinion polls that are guiding his policy.

Cameron or Brown: it's your choice. Or is it? Actually, the reality is you're unlikely to have very much influence on the result.

If you live in a safe parliamentary seat where one party dominates – which more than 70 per cent of us do – your vote will be wasted if you cast it for the candidate who expects a stonking majority with or without your help.

Your vote will also be wasted if you give it to any of the hundreds of candidates who know they are going to lose even before they begin the campaign – because that is how the electoral system is rigged.

Only if you are fortunate enough to live in a marginal constituency will you be able to express your democratic choice, albeit one between two similar-looking and similar-sounding party leaders.

Is it any wonder that turnouts are plummeting? No party in the history of British democracy has ever had the support of 50 per cent of the electorate, and incoming prime ministers regularly describe the support of 30 per cent of the population as an overwhelming mandate.

But things are getting worse. At the last general election, in 2005, Tony Blair was returned to power by just 21 per cent of those eligible to vote.

Both Labour and the Conservatives, meanwhile, have seen dramatic falls in party membership over the last 20 years, despite their frantic attempts at political cross-dressing.

As a nation, we find politics a big turn-off – and this spells disaster. How low can turnouts go without the elected government losing all claim to legitimacy?

How far will political activism slump before all parties become minority parties? This is no fit state for a state to be in.

You would have thought politicians would feel an urgent moral duty to address the problem of mass disengagement, but either they don't want to do anything or don't know what to do.

It is true that it is not entirely their fault. The British constitution, such as it is, wasn't devised by dispassionate sages thinking of the general good; it was cobbled together through a series of face-saving expediencies and compromises.

Its guiding principle is that if an institution works in a muddling-through fashion, we shouldn't tinker with it.

That is hardly a safe recipe for a 21st-century democracy that seeks to lecture other countries on how to do parliamentary democracy.

The media compounds the problem by fostering a culture in which image, spin and soundbite generate more news than integrity, honesty and the long-term application of common sense for the good of the nation rather than the loudest interest groups.

And we, the public, are now little more than docile spectators, becoming ever more disappointed and cynical with the circus that passes for current affairs.

From ground level, you get the impression that all politicians are deceitful and untrustworthy, and nothing ever changes for the better, and there is nothing we can do except leave the clowns to it.

But we should not surrender our democratic birthright so easily. Politics is an important business. It can destroy jobs; start wars;
fail to educate our children; let us down when we get sick, and squander our taxes on futile bureaucratic projects.

And politics does not have to mean party politics. The subject goes much wider and deeper than that. Wherever you've got two or more people together – in marriages, in workplaces, in schools – you've got a political dynamic. There is politics in The Simpsons and politics in the world of Harry Potter – a Minister for Magic who tells the actual Prime Minster what to do.

We need to increase the level of political literacy in Britain, to rewaken the art of informed, non-partisan public debate.

To see past the celebrity-worship and Westminster gossip that makes up so much of the reported news and address the issues that
really matter.

And first we need to articulate the vital question of how we want to be governed, not just by whom.

Nick Inman is the author of Politipedia, a collection of useful and useless political facts published by Harriman House (www.harriman-house.com/politipedia).