JOHN PRESCOTT did not mince his words when evidence of a

disastrously low turn-out came through late on Thursday night. ''I'm concerned about complacency. This low vote is bad for democracy,'' the Deputy Prime Minister warned.

He has cause to be worried. More than 20 million English voters had a chance to choose local councillors and, in London, register a view on whether the capital should have a directly elected mayor. In the end, fewer than a third bothered to vote.

In some areas the poll fell towards 20%, down to levels which could legitimately be said to invalidate the outcome. An organised party with the support of just 12% of the electorate could seize control.

The Prime Minister echoed the anxieties voiced by other party leaders as he reacted to Labour's ambiguous showing in its first electoral test since the General Election. The low turn-out, he said, would reinforce the Government's determination to modernise local government and make it more relevant to ordinary people.

Analysts will now focus on establishing just why so many voters showed not the slightest interest in participating. Apathy must have a cause. Does local government matter anymore? Is politics dead? Or are we just plain Blaired-out after last year's excitement?

There was a time when all politics was local. The phrase, coined by the late Tip O'Neill, one of the greats of post-war politics in Massachusetts, encapsulated the importance of grassroots democracy. Participation, even if it meant doing the machine's bidding, was everything.

Not any more. We live in a centralised democracy, where power is concentrated in the hands of the executive in Downing Street and its subsidiary departments in Whitehall. Parliament, itself obsessed by its

own sovereignty, presides over the decisions - once they are taken.

No wonder we don't vote, this persuasive logic goes, we know it

doesn't matter.

Tony Blair wants to change all that. He has set in train the unbundling of the United Kingdom with a programme of devolution that will hand power back to Scotland, Wales, the regions of England, Northern Ireland, and even the great metropolitan bodies. He aims to reverse the decline of local accountability and responsibility accelerated under Margaret Thatcher.

The turn-out was only marginally better in the London referendum, but still low enough - at 34% - to cast grave doubts on one of Labour's flagship constitutional reforms. Two-thirds of those who voted said yes, but that means only about one million of 10 million Londoners could be bothered to express a view on how the city should be run.

Local government never recovered from its treatment at the hands of Mrs Thatcher. The excesses of Militant, of Loony Lambeth, of ''Red'' Ken Livingstone and the Greater London Council, gave her Government the excuse it needed to transfer powers to the centre.

From a Victorian peak of far-reaching civic authority, today's councils are reduced to little more than scapegoats, limited by diktats from Westminster on everything from spending to education provision. Even the rubbish collection has been contracted out to barely accountable private operators. A succession of sleaze scandals, the majority in Labour-dominated areas, has further undermined local government's credibility. Local government, the voters seemed to say yesterday, just doesn't matter.

Liberal Democrat local government spokesman Jackie Ballard last night blamed Thatcherism for the apathy. The solution, she said, was for Labour to return powers to councils ''in a genuine way'' and to ''take seriously the call for proportional representation in local government elections''.

Dr Tony Flower of the Joseph Rowntree Reform Trust says the poor turnout could have dangerous implications for the London project. ''It's all to do with legitimacy. It's the same difficulty we had in Wales, where devolution was endorsed by a slender majority. A low turnout makes the mayor and the assembly that much harder to justify. Its enemies can always say that a majority refused to endorse the proposals.''

On the wider question, Dr Flower blames election fatigue for England's indifference to the democratic process. ''We put so much into getting rid of the Tories that I think people just couldn't summon the energy again. It's worrying, but it was to be expected at this point in the electoral cycle.''

Already the turnout has been seized on by trade unionists, who pointed out yesterday - rightly - that if a 34% poll was enough to give London a mayor, then it would be impossible for the Government to set a higher threshold in its legislation for trade union rights, due within weeks.

The Government will begin work to identify how to encourage participation. We can expect moves to give local councils a greater say in the issues that affect people's lives. John Prescott's environment department is looking at ways of involving authorities in transport policy. And, sources say, there will also be an examination of the mechanics of voting. In the information age so beloved of New Labour, pencils, slips of papers and fixed voting hours begin to look seriously outdated.