By Brian Wheeler
Political reporter, BBC News, Lib Dem spring conference, Harrogate
A personal appeal by Lib Dem leader Sir Menzies Campbell has helped him win a narrow victory over Trident rebels at his party's spring conference.
Sir Menzies is faced a challenge over his Trident policy
Sir Menzies appeared on stage to defend his policy of delaying a decision on replacing Britain's nuclear weapons.
Opponents, including some of his own MPs, wanted Trident to be scrapped when it reaches the end of its life.
Sir Menzies wants the number of warheads cut by 50% now, but a decision on replacing them delayed to 2014.
He won the vote by 454 votes to 414, after an initial show of hands had been too close to call.
The result will come as a boost to the Lib Dem leader, who has faced questions about his style of leadership
Party managers said afterwards that Trident rebels would probably have won without his intervention.
MP Phil Willis, who led opposition to Sir Menzies said although he was disappointed to have lost, the leader's victory would come to be seen as his "Clause 4 moment," referring to Tony Blair's historic scrapping of Labour's commitment to public ownership.
"He answered his critics today," said Mr Willis, a former frontbench and the local MP.
Sir Menzies, who had not been due to speak, was called to the stage in Harrogate - to the evident surprise of many delegates - to deny he was "sitting on the fence".
In an impassioned speech, he argued that his policy of cutting the number of missiles by half while leading global disarmament talks was the only "rational" approach.
And he said Lib Dem MPs would be voting against government plans to renew Trident whatever happened.
"I only know one way to lead and that is from the front," he told delegates.
But, far from backing nuclear weapons, his proposals were about disarmament and "about cutting Trident by half now".
The rebel amendment, on the other hand, would see Britain keeping Trident until it reached the end of its useful life, before scrapping it.
"What on earth is radical about preserving the status quo?" Sir Menzies asked delegates.
He said government plans to renew Trident, at a cost of £65bn, were part of a "desperate attempt" by Tony Blair to "shore up his own legacy".
And he said Liberal Democrats would not "fall into Blair's trap under any circumstances".
Cancelling the replacement for Trident now would do nothing to help the cause of disarmament around the world, he argued.
But his proposals were a "rational and perceptive response" to the situation, which would give Britain influence in non-proliferation talks.
Sir Menzies was backed by frontbench colleagues Simon Hughes and defence spokesman Nick Harvey, who both spoke in favour of his proposals.
Speaking afterwards, a clearly relieved Sir Menzies said he was "obviously pleased" with the result, as he believed it was the "right policy".
He told BBC News 24 it was an "indication of the maturity of the party that we could have that debate," something he claimed would not have happened at a Labour or Tory conference.
He said that by "by 2014 we will have a much better idea of the strategic environment and whether nuclear weapons are still necessary," with potential threats from countries such as Iran and North Korea.
The revolt against the official party line was led by Phil Willis.
He said the "wait and see" approach would discredit the party, encourage proliferation and tie the UK into US foreign policy.
'No turning back'
And he attacked as "pure misrepresentation", the leadership's claims that the amendment would result in Britain keeping Trident for 20 years.
"What are we waiting for?" he asked activists. "Blair is making the decision not in four years' time or five years' time; he is making the decision this month.
"And once this multi-million pound programme is embarked on there will be no turning back.
"Postponing a decision sends out a clear signal, that our party is prepared to support new improved weapons of mass destruction some time in the future. Is that what this conference wants?
"If the Liberal Democrats are to be relevant, we must be prepared to be different.
"Waiting will not make nuclear weapons less dangerous, nor will it make them more ethical.
"Waiting will not kick start disarmament, it will encourage proliferation.
"Waiting will not help influence rogue states to give up their nuclear ambitions; why should they respond to a policy of 'do as I say not as I do?'