The United Kingdom has given a resounding thumbs down to proposals for electoral reform in a nationwide referendum.
With almost three-quarters of the votes counted, the No campaign had established an unassailable lead of around 69% to 31%, securing victory in almost every corner of the country.
Senior Liberal Democrats - who had led the campaign for the Alternative Vote - conceded defeat and acknowledged that their long-cherished dream of electoral reform is now off the agenda at least until the end of the Parliament.
The rejection of AV, under which voters rank candidates in numerical order, was a further humiliation for Deputy Prime Minister Nick Clegg, for whom a referendum on voting reform was his main prize in negotiations to form a coalition last year.
But prominent Lib Dems insisted that, despite the setback on electoral reform and the party's disastrous showing in elections to English councils, the Scottish Parliament and Welsh Assembly, Mr Clegg's position was safe and the coalition would survive.
After 296 of the 440 referendum declarations, the No campaign had 68.56% of the vote against 31.44% for Yes. Only the inner London boroughs of Islington, Haringey, Camden and Lambeth, the city of Cambridge and Glasgow Kelvin had backed AV.
Liberal Democrat Cabinet minister Chris Huhne accepted that there would be no further attempt to introduce voting reform during this Parliament and that it was "over" for the Alternative Vote.
But he appeared to leave the door open for the Lib Dems to attempt to introduce some other, more proportional, system in the future, telling Sky News: "I think it is over for the Alternative Vote. I think it is very clear that the people have spoken, that the Alternative Vote is not a runner and we must respect that decision."
Voters had not expressed an opinion on proportional representation (PR), he said. "The question on the ballot paper was 'Do you support AV?' and we must respect that," said Mr Huhne.
Mr Huhne - who was vociferous in his criticism of the Conservatives' conduct of the AV campaign - said it was "ridiculous" to suggest that Mr Clegg should lose his position or that the Lib Dems should quit the coalition.
"We have a coalition agreement which we have pledged to deliver and we plan to go ahead with it," he said.
Labour former Cabinet minister Lord Reid, one of the No campaign's most vocal frontmen, said the public had delivered a "resounding" rejection of AV.
He warned the Liberal Democrats not to look for any "back-door" introduction of voting reform, such as pushing for PR in elections to a democratic House of Lords.
"The British Constitution is not some bauble to be handed out as a consolation prize. It would be an outrage if such a resounding vote was to be ignored by the Liberal Democrats," said the former Home Secretary.
The Electoral Commission said a total of 18.6 million votes were cast in the AV referendum across Great Britain, giving a provisional turnout of 41.8%. But this figure does not include Northern Ireland.
Labour supporters of electoral reform blamed the defeat on Mr Clegg's decision to stage the AV vote on the same day as other polls, limiting the scope for cross-party campaigning at a time when they were pitted against one another for council and assembly seats.
Labour grandee Lord Mandelson said: "Nobody could have foreseen the extent to which the whole vote over the last 24 hours has become a referendum on the Liberal Democrats in general and Nick Clegg in particular.
"We paid a big price for combining the AV referendum with the first elections to be held following the General Election last year."
Lord Mandelson was critical of the handling of the Yes campaign: "The ground work was not done for this referendum. I think that the public felt the thing had come out of the blue as the result of some arrangement between the coalition partners and they didn't see why AV was such a big deal.
"I don't think they felt AV was the solution to many of the problems they feel are in our political system."