Leading article: The contest is local, the significance national

Most mayoral elections tend to be parochial affairs, focusing on issues of only marginal relevance to the rest of the country. But Thursday's vote to decide the outcome of the London mayoral contest will be a political event of truly national importance.

Indeed, the capital has become something of a proxy battleground for the main political parties in recent weeks. Boris Johnson has been thrust forward as a representative of David Cameron's modernising Conservative Party; with its new emphasis on inclusiveness. Meanwhile, despite his historic differences with the Labour leadership, the incumbent, Ken Livingstone, has attracted the personal support of Gordon Brown on the stump. If Mr Livingstone's campaign had to be boiled down into a single message it would be "vote for competence and experience rather than charm and flashiness". The parallels with the Prime Minister's own situation are clear.

If Mr Johnson is victorious, it will be a significant boost for the Conservative Party; it will be interpreted as a sign that the national mood is turning back in its favour. Labour will likewise feel some welcome wind in the party sails if Ken Livingstone is returned for a third term of office in City Hall.

So much for the politics; but who deserves to prevail? Mr Livingstone has a lot to be proud of from his eight years in power. His record on transport, the policy area over which the Mayor's office has most power, has been significant. He has increased the number of buses, encouraged Londoners on to their bikes in huge numbers and reversed the trend of rising car congestion. In terms of community relations, he has been a success too. Mr Livingstone has celebrated London's cultural and ethnic diversity, rather than fretting about it, as too many politicians on the national stage are prone to. He has also been far bolder on the environment than national government. It took genuine political courage for Mr Livingstone to introduce the Congestion Charge.

But the present Mayor has just as much that he ought to be ashamed of, namely his profligacy with public funds and his naked cronyism. On a personal level, Mr Livingstone has displayed arrogance and an unattractive sense of entitlement during this campaign. He has also, at times, looked physically tired.

Yet it is not enough for one candidate to look past his sell-by-date. Another must inspire. The Conservative mayoral campaign has been tightly-run and professional; its tactics have been largely based on reining in its candidate's more flamboyant instincts. But for all that, it is hard to see even the new, more serious, Mr Johnson as Mayor of a world city such as London. The Conservative candidate has never shown any real interest in the capital in the past. Nor does he have any experience of public administration. And the innate cautiousness of his campaign means that, in policy terms, he has outlined nothing much to excite Londoners.

The representative of the third party, Brian Paddick, has been disappointing too. He has overplayed his experience as a Metropolitan police commissioner, focusing on crime to the exclusion of other important issues. Thankfully, Sian Berry, the Green Party candidate, has been much more engaging. Though she has inevitably struggled to attract as much publicity as the other three candidates, she has still managed to articulate a serious environmental agenda.

Yet, aside from odd flashes of brilliance, or belligerence, there has been nothing really to bring this campaign to life. For all its wider political significance, this has not been the inspiring democratic contest that a city like London deserves.