It was a surreal sight: John Redwood, the champion of Thatcherism, speaking at a Labour conference and putting a socialist case.
By Ollie Stone-Lee
BBC News Online political staff
Fortunately for delegates who might have wondered if they were still under the influence of those late night conference tipples, Mr Redwood's later clashes with Europe Minister Denis MacShane proved Mr Redwood had not suddenly changed his political spots.
He was just trying to give himself a chance with an audience not exactly predisposed to give him a favourable hearing.
The ex-Cabinet minister and Tory frontbencher faced Mr MacShane at the Foreign Policy Centre's fringe meeting about the proposed European constitution.
"I come here today not as a Conservative - I am sure that might not gain me many laughs or much applause - but as a democrat," he began.
Mr Redwood said party political opponents often forgot the things which brought them together.
But there were guffaws as he announced, smiling: "I've re-read the treaty from a Labour perspective. I feel your pain because I know you have been let down by your government."
MacShane says the debate is at a defining moment
That phrase signalled that the Wokingham MP was not exactly going to temper his views just to get an easy ride.
He argued the changes proposed in the constitution would damage Britain's ability to act in the areas Labour supporters held dear - on customs, trade, social policy, transport and the environment.
The constitution meant Europe would have "shared competencies" in most areas of government activity and were not proper sharing between partners.
"Shared competence with the European Union is rather like the pig agreeing with the chicken to go into the breakfast business together," said Mr Redwood.
The scheme worked well for the chicken, who just had to provide the eggs, but spare a thought for the pig making up the bacon.
Levers of power
He appealed for Labour activists to make "common cause" in following democracy and stopping control going to unelected officials.
"This constitution is about taking the main levers of power away from you, away from me, away from the constituents I represent," he argued.
His criticisms were most strident over foreign policy as he said decisions over going to war in Iraq should be made in Britain, not Brussels.
And he claimed the UK would have a seat but not a voice on the UN Security Council because the constitution obliged member states not to "impair" the EU's common foreign and security policy.
That claim was branded "outrageous" by Mr MacShane, who emphasised that every EU country would have a veto over European foreign policy.
Nobody in France would believe their foreign minister was going to give up control over its international outlook, he argued.
He launched a fierce assault on the "myths" spread around by Eurosceptics, including some from Tory leader Michael Howard.
There was going to be no United States of Europe, trial by jury was not under threat, asylum policy would still be decided at home and the British monarchy would not be replaced by a European head of state.
Mr MacShane argued the debate was at a defining moment in the run-up to the referendum over the constitution, which he did not think would be before the next general election.
He ribbed his Tory opponent, asking him to send Michael Howard his thanks for bringing Mr Redwood back into the shadow cabinet.
But he said pro-Europeans had not found the language to make their case, which was nuanced and complex talk about coalition and compromise.
He admitted: "John and his friends and colleagues have probably got the best tunes."
Mr MacShane said he welcomed healthy scepticism about the EU and debate but convinced the pro-European arguments would win.
But he added: "What we explain to our people is that Britain's role in Europe is good for their jobs, good for their economy, for their social rights."
As the questions got under way, Mr Redwood immediately discovered there was somebody less popular than him in the room - the UK Independence Party member got heckled.