Leading article: If newspapers had a vote, this one would put its cross beside...

Local council elections are frequently dismissed as being of no more than local significance. The sparse turn-out often suggests that, even locally, they are not rated as serious opportunities for democratic participation. In both respects, however, today's elections – being held for some 4,000 seats on 159 councils in England and Wales, for London mayor and for the London Assembly – are different.

As the first elections of any kind to be held since Gordon Brown took over from Tony Blair as Prime Minister last summer, they will inevitably be seen to an extent as a referendum on Mr Brown's performance. This has been, and will be, fiercely denied by those whom it does not suit. But that does not alter the fact that many voters had geared themselves up for an election last autumn and felt cheated when none was called.

Whether people are influenced by the national picture when they use their votes today, or confine themselves to important local issues – such as housing or bin collections – the major parties all understand that the results will be interpreted in a national light. This is why Labour in particular, but also the Conservatives, have been so desperate to dampen expectations.

It is to Labour's advantage that the equivalent local elections four years ago took place in the shadow of the Iraq war. Labour's poor showing then means any loss of seats today should be limited. Then again, if Labour losses are high – as the fragile state of the economy and Mr Brown's lacklustre performance since changing jobs suggest they could be – discontented MPs could increase the pressure on the Prime Minister.

The results will also be a moment of truth, albeit a less weighty one, for the Conservatives and the Liberal Democrats. These elections will be Nick Clegg's first as party leader. Polls indicate that the party's fortunes have picked up since he took over, but today will be the test. David Cameron, for his part, should discover how far his party's current double-digit lead in national polls translates into actual votes and council seats. Of particular significance will be the party's showing outside the south of England. This will reveal how far, if at all, Mr Cameron has been able to extend his party's appeal.

Compared with the relatively low-key contests taking place in most of the rest of the country, the election for London mayor has turned into a real battle of personalities, style and wills. We might regret that the leading candidates were so flawed, but a really neck-and-neck race between distinctive personalities is too rare an event in British politics not to be enjoyed.

A win for the Conservative candidate, Boris Johnson, would be hailed as proof that the Tories have a real chance of returning to national government. Mr Brown's adversaries in his own party would use the loss as another stick with which to beat their beleagured leader.

If the present mayor, Ken Livingstone, manages to hang on, Mr Brown will have salvaged something from what looks likely to be wreckage elsewhere in the country. A strong performance by the Liberal Democrat, Brian Paddick, or the Green candidate, Sian Berry, would also be seen as straws in the national wind. Like it or not, London's mayoral election is a contest with implications for the country as a whole.

First and foremost, though, the implications are for the capital. Here, voters can revel in the breadth of the choice before them. The transferable vote system makes the result a fairer reflection of Londoners' will than a narrow victory under first-past-the-post. It also gives everyone the rare chance to make their votes count.

The obvious choice is between the incumbent, Mr Livingstone, and Mr Johnson, the MP and former magazine editor. In vividness and character, Mr Johnson has added much to the campaign – though not as much as if his handlers had let him off his leash. Despite a new, serious, mien and some interesting ideas, however, there remain doubts about his temperament and ability to run a city as big and important as London.

Mr Livingstone has often appeared world-weary on the campaign trail, and at times exasperated with the very idea that he faces competition – which could be an argument for introducing a two-term limit. And while we have genuine questions about his managerial practices and the huge machine he has built up, he has proved his ability to tackle the serious problems London faces and the big projects that are in hand.

While the benefits of the Congestion charge have been hyped, Mr Livingstone's courage in introducing it, his commitment to public transport, his early espousal of green politics and the emphasis he has placed on the "living" wage and affordable housing have improved the capital. We also dislike the vendetta waged against him by London's single paid-for newspaper.

As for the second-tier candidates, Brian Paddick has, frankly, been a big disappointment. He has found it harder than we expected to graduate from senior copper to politician. Sian Berry, for the Greens, on the other hand, has been an articulate, imaginative and effective advocate for her cause. With her programme for a greener London, with more cycle-lanes, cheaper public transport, more small shops and eco-friendly housing, she has come across as a forward-looking politician, committed to a better quality of London life. We hope she can continue to find a voice in the national debate.

So consonant are her priorities with those of this paper that, if we could vote for mayor today, we would place our first-preference cross against her name. This would underscore the importance of the environment to both London and to the rest of the nation. Then, and with rather heavy heart, it would be illogical to do anything other than make Ken Livingstone our second choice.

Your vote, of course, is up to you – but please use it, if you have the chance.