The new boy on Britain’s political block is a bright chap. To enter parliament at your first attempt can be luck; to win the party leadership just two years later suggests ability. But can Nick Clegg, the new Liberal Democrat leader, break the mould in which his colleagues have been trapped for almost a century? The answer is probably no.

British Liberals are the most fantasist politicians on the planet. They have never come near winning power in a general election since universal franchise was introduced in 1918. Their notional strategy of building a new strength on the centre ground has failed utterly, even when conditions were overwhelmingly favourable in the mid1980s.

History’s message could hardly be clearer. The left of British politics belongs to Labour, as refreshed in the 1990s by Tony Blair; the right to the Conservatives, as refreshed by David Cameron. There is no room for Liberals (or Liberal Democrats as they meaninglessly renamed themselves). They are a protest vote, a dustbin vote, a transient vote, a one-issue vote, a none-of-the-above vote.

Yet these also-also-rans endure a living death, propped up with public money, a strong base in local government and Westminster’s culture of fair play. No debate is complete without a Liberal Democrat present. And they periodically compel us to review the political map of Britain by electing a new leader.

Clegg appears to be in the long tradition of Jo Grimond, Jeremy Thorpe, David Steel, Paddy Ashdown and Ming Campbell. Like them he speaks in platitudes. Like them he has found a few distinctive policies that come easily to those who know they will not have to implement them, as on identity cards, penal reform, drugs and local taxes. Although a “new” politician with a young family, presentable and internationalist, Clegg lacks the key quality of his ilk, a personal narrative and an idiosyncratic style. His slogan is the dreadful Blairite cliché, “ambition and change”. He cannot conceal the impression that he would sit equally happily in a Brown or a Cameron cabinet.

Modern democracies love duopoly. They flirt with third parties and maverick candidates, but in the out-turn they prefer a clean choice: Democrat/Republican, Christian Democrat/Social Democrat, left and right.

Britain’s Liberals were supplanted by Labour as soon as the working classes and women won the vote and have never found a place on the spectrum since then. They have become a comfortable Westminster club, as in the age of Walpole and Pitt.

Hence what should be the great Liberal Democrat issue – which of the two other parties should be supplanted – has become the great dither, a dinner table chat. It was the one question from which both Clegg and his opponent, Chris Huhne, fled with horror during their leadership campaign. Neither wanted to be thought more left wing or more right wing than the other. They grasped in desperation at such vacuities as progressive, radical, inclusive and pro-change. Each was more beige than the other. This might work for a big party seeking to colonise the centre, but not for a centrist party out to capture a particular fringe.

Instead, Liberal Democrats have again joined in that ruling obsession of centre parties, what to do in a hung parliament. How might they exert tangential power through a coalition or parliamentary pact?

Liberal Democrats fondly believe that their support in a hung parliament can be bartered for proportional representation, in a form that would give them the long-term balance of power and make them kingmakers in perpetuity, as they are in much of local government. There is no shred of evidence for this strategy.

Hung parliaments come to Britain barely once in a political lifetime. The last was in the 1974 parliament and was disastrous for the country and for the Liberals. Neither Tory nor Labour leaders are inclined to such a suicidal barter. It would also spell the death of emphatic election results, one of the few boons in the British constitution. Blair’s humiliation of Ashdown after flirting with him in 1997 is merely the most glaring example of this.

Clegg can flit along like his predecessors as a centrist gadfly. He can score flesh wounds on the government over Northern Rock and Iraq. He can hint at novelty over local taxes or imprisonment. Labour can be assailed as stingy over education and health, the Tories as little Englanders over Europe. As long as Liberal Democrats are indulged at Westminster, Clegg can go on treating politics as about argument rather than power. He can be the nation’s comfort blanket.

Parties are no longer clubs. They represent movements, interests, bodies of opinion. They must choose what they wish to represent. The old divide between left and right has been eroded by prosperity, reflected in falling turnouts, declining party membership and whimsical opinion polls. The two big parties have become centripetal, grabbing at whatever appears to dominate the mainstream. Liberal Democrat support has been doubling and halving in response to such raids on their ideas, but its public image has depended almost entirely on that of its current leader at Westminster.

In reality left and right are not dead. They still carry the baggage of poor versus rich, central versus local, collective versus individual. If Clegg really means to be radical, then he must choose which radicalism. He must become more Labour than Labour or more Conservative than Conservative. In traditional terms, he must outflank one or other from their wings.

Away from the comfy centre, life gets suddenly nasty. On the right lies a new and virulent scepticism towards all government. This view is anticentralist, in favour of small business and averse to Gordon Brown’s authoritarianism. It wants to keep local post offices, schools and cottage hospitals. It is chauvinist but also mercantile, like Victorian Liberals. It is sceptical of Cameron’s progressivism and deplores his inability to find a truly libertarian narrative.

Clegg’s party might have moved towards the Tories in the 1980s, when the latter were deeply split by Margaret Thatcher and when a “Liberal-Conservative” coalition might at least have been a possibility.

Such a prospect was killed stone dead when Labour split and the Social Democrats seduced the Liberals into a foolish belief that together they might supplant Labour as the moderate party of the left. Nor can Clegg run as a plausible champion of this form of right-wing liberalism, given his lifelong commitment to that most corrupt of centralist regimes, the European Union.

The left offers more fruitful ground just now. It is a political wasteland of demoralisation, of Labour’s abandoned allies among trade unions, council estates and the antiwar movement. In the 2005 election, one in four Liberal Democrat voters said he or she would have voted Labour but for Iraq. These antiLabour leftwingers must be held and exploited.

“Lib-Lab” has long been a seductive cry on the left and strategists might argue that another stab at 1981 might be worth trying. For that, Clegg must outflank Brown on the left in the most explicit terms. He must promise to introduce higher redistributive taxes, throw money at social services, end creeping selection in schools and liberate trade unions.

Liberal Democrats must become the party of national collectivism, promising to deliver on Brown’s target-driven state better than he has. If Labour is to be crushed by the Tories at the next election, the Lib Dems must be strategically placed to become the official party of the new left. They must present themselves as “real Labour” as from now.

I find neither strategy particularly plausible. But Clegg must choose. He cannot lead first one way and then another, as if the 20th-century Liberal experience had taught his party nothing. He must find a message rooted in one of the two core ideologies that have, if at times imperceptibly, underpinned British politics. Only then can he lead his troops confidently into battle.

The trouble is that on the showing of his election campaign, Clegg embodies neither side of this choice. Nor has his election offered him any guidance. Like his benighted party, he is gripped by indecision, caught in the mushy middle, not knowing which way to turn.

Times Recommends

• Treat Africans as part of the human jigsaw
• Too bitter a pill for me to swallow
• This Bill is a panic measure in a tarnished age