The idea of deserting Labour just as it is about to win power may seembizarre. But some radicals are doing just that. Michael Mansfield, the radical QC, said last week he was so revolted by Labour's failure to defend civil liberties that he had given up on the party and did not know where to turn. "There's no possibility of dissent in the brave new Labour world," he said. "Vote for them? Give me a break."
Almost weekly you can hear the sound of pennies dropping as people and organisations who vaguely felt the Labour Party represented them realise that it may not. Last week it was the turn of activists engaged in the unglamorous and presently hopeless cause of prison reform. They had been round the Commons warning the few politicians who would listen that the overcrowded jails could explode in the coming months.
Alan Beith, deputy leader of the Liberal Democrats, listened hard. He nodded away as they told him there were far too many people in prison, that the crammed cells were a scandal perpetrated by an opportunist Conservative Home Secretary interested in approving headlines in the Daily Mail, not in reducing crime.
When they got to Jack Straw, Labour's home affairs spokesman, their reception was very different. There could be no guarantees that the prison population would drop under a Labour government, he said. The party must be seen to be tough at all times.
"Bloody hell," Harry Fletcher, from the probation officers' union, said afterwards, "the Lib-Dems are more progressive than Labour. I may even have to vote for them."
"I'm a Labour Party member," a second member of the delegation said, "but I'd happily support the Liberal Democrats if they had the best chance of winning in my constituency."
Should they? Should you, if you consider yourself left-wing or even pale pink?
Most Labour intellectuals would regard the question as ridiculous. The compelling need is to get rid of a hated but successful Conservative Party which increasingly seems like an agit-prop caricature of arbitrary and corrupt privilege. In most constituencies the best way to remove a Conservative is to vote Labour.
There is also a comforting but rarely expressed belief that the Labour leadership cannot mean what it says. When right-wing newspapers applaud Tony Blair for flying to the other side of the Earth to pay court to Rupert Murdoch or for charming the CBI conference, the silent, mocking response has been: "You fools, don't you realise that once Labour is in power it will attack aspirant monopolists and the overweening power of modern management and the City?"
But Mr Blair may not be lying at all. He may well mean what he says. And what he says is hard to recognise as socialism in traditional, modern or any other clothing.
Here he is at the CBI conference earlier this month on taxing the rich: "I want a tax regime where, through their hard work, risk and success, people can become wealthy. Let me say for the avoidance of doubt, Britain needs successful people in business who can become rich by their success, through the money they earn."
In May when he gave the Mais lecture at City University, London, he cut the ground from under Labour supporters who believe the City deprives industry of the long-term funds needed to develop new products and generate jobs. Concerns about the absurdly high real rates of return for shareholders on new investment (20 per cent a year compared to about 8 per cent in Germany) were dismissed. There was, he said, no question of Britain importing the long-term financial policies of Germany and Japan. The relationship between finance and industry in different countries "reflects a number of different historical and cultural factors that cannot be transposed".
And when Mr Murdoch closed the Labour-supporting Today newspaper, even though there was a potential buyer, Mr Blair did not condemn him but came close to urging its readers to buy the Murdoch-owned Sun instead.
Just after Mr Blair first became leader, one member of the Shadow Cabinet came out of a meeting and said: "He's not a social democrat, he's not even a Liberal Democrat, he's a Christian Democrat."
To the Labour leaders, such accusations of betrayal are ludicrous. Mr Brown is developing a radical economic policy, they say, which will include measures to reform the City; in his Mais lecture, Mr Blair attacked excessive deregulation and stated his "passionate belief" in building a fairer society by improving education and opportunities for all.
More important, they are beside the point. "Look," said one Blair aide, "we are trying to build a centre-left coalition which can win in a country which has had Conservative governments for 75 of the past 100 years. This is serious politics which the Liberal Democrats don't begin to understand."
But if it is a left-of-centre coalition, it is fair to ask where the centre is. Even new Labour's natural intellectual allies can sometimes be surprised at the timidity of the party's leadership. The Centre for Economic Performance at the London School for Economics is home to a cluster of new-Labour and thoroughly modern economists. No one would describe the centre as socialist. Its academics criticise previous Labour governments for unthinkingly supporting the Keynesian belief that economic growth would inevitably benefit the poor. Paul Gregg, a member of the centre, is quite happy with Mr Brown's plans to slash the lower rate of income tax to 10p, though Dr John Wells, an adviser to John Smith, announced that he was resigning in protest against the attempt "to steal the Tories' clothes".
For Mr Gregg, Mr Brown is a radical who has woken up to the fact that policy needs to be targeted on the poor, the 19 per cent of the population who, although they are of working age, live in homes where no one has a job, the low paid and part-time workers.
However, adds Mr Gregg, the reverse side of the phenomenal growth in poverty since 1979 is the shift of money to the wealthy. Average wages of the top 10 per cent of earners have risen by 5 per cent a year every year the Conservatives have been in power. The top 25 per cent of full- time earners now receives 50 per cent of the wages.
"If the trend for more and more wealth to be concentrated in the hands of fewer and fewer people continues, Labour will not be able to redistribute much to the poor," Mr Gregg said. "But I see no plans to tackle the people at the top."
There are other gaps. Trade union leaders did a deal with the Labour leadership before last year's conference. Give us a minimum wage, employment rights and the European Social Chapter, they said, and you can do what you want. But, after the conference, in his CBI speech, Mr Blair said that he had no intention of implementing all social legislation coming out of Europe. Labour's health and constitutional reform plans remain vague and few would be surprised if it shifted further towards supporting grant-maintained schools.
Yet the Liberal Democrats seem to offer certainty. They are committed to renationalising Railtrack; Labour is not. They will raise taxes on the wealthy, Labour won't say what it will do. They will raise standard- rate income tax to improve education; Labour cannot say where the money will come from. They support human rights and oppose harsh anti-crime policies; Jack Straw wants to clamp down on squeegee merchants.
This does not mean they are more concerned with inequality than Labour. Paddy Ashdown's Liberal Democrats can sometimes appear to see the poor as objects of pity and to be unhappy when they demand rights. Peter Hain, a former leader of the Young Liberals and now a left-wing Labour MP, argues that the Liberal Democrats' hostility to trade unions and their unwillingness to promote social justice by restricting the free market leaves them well to the right of Labour.
The one big carrot the Liberal Democrats offer those who still believe in fundamental change is constitutional reform.
Democratising the House of Lords, abolishing quangos and giving people some power to control their lives through local government are good democratic principles in themselves. Proportional representation, with the opportunities it brings for small parties, raises theprospect of a realignment of politics. Labour is committed to holding a referendum on PR but it is not clear if it will support change when and if it fulfils its promise. Earlier this year Mr Blair said he was "unpersuaded" of the merits of reform.
At present the Labour and Conservative parties are each coalitions, though each tries to hide the differences within them. Genuine public debate on serious issues is stamped on in the name of party unity - as Clare Short found when she dared to discuss the drugs problem.
Proportional representation would force the deals between the factions to be made honestly, in the open and in front of the electorate. It would allow the Christian Democrats and English Nationalists in the Conservative Party to split away. It would also allow Labour to split. The Blairists would probably remain the stronger force, but the rest could form what Britain does not now have, a genuinely left-of-centre party.