Ed Miliband will eventually come around to supporting an in/out referendum on Britain's membership of the European Union a Labour MP has predicted, as the party refused to rule out a change to its position.
Glasgow MP Ian Davidson told the Commons on Friday morning that his party's poolicy was "in a state of flux" over the issue.
"It's at present a caterpillar that in a short time will emerge as a butterfly. I believe that we will change our position in a relatively short period of time as events change themselves," he said.
He was speaking as Conservative MPs packed into the House of Commons to support the Private Member's Bill tabled by Tory backbencher James Wharton, which would require an in/out poll by the end of 2017.
Highly unusually for backbench legislation, David Cameron and other senior ministers including George Osborne and William Hague were positioned prominently on the front bench to hear Wharton introduce his Bill.
By contrast, the Labour and Liberal Democrat benches were sparsely occupied, with the bulk of the parties' MPs obeying the guidance of their leaders to stay away from a debate which they regard as a political stunt.
The Bill easily passed its first Commons hurdle, with 304 MPs voting in favour and zero voting against - as Lib Dem and Labour MPs had chosen to ignore the vote.
Miliband - who was absent from Westminster today - came under renewed pressure on the eve of the vote to commit Labour to a public vote when one of his frontbench spokesmen broke ranks to call for a vote to be held even sooner than under Cameron's plans.
Dudley North MP Ian Austin, a former aide to Gordon Brown, wrote in the Express and Star newspaper: "The truth is that the UK needs to decide and I would prefer it to do so more quickly. I know this isn't Labour Party policy, but my view is that we should have a referendum next year on the same day as the European elections."
Speaking during the debate today, Labour shadow foreign secretary Douglas Alexander refused to rule out a switch in the Labour position - simply saying any policy would be decided based on the "national interest".
Hague drew laughs from MPs today as he was easily able to paint Labour's decision to abstain on the Bill as being "shrouded in uncertainty" and one characterised by "unmitigated dither and confusion".
The foreign secretary mocked the apparent divisions within the shadow cabinet - noting that Miliband has said he does not support a public poll while Ed Balls has indicated there could be one.
He said Labour MPs were split, with "some in favour, some against, some adamantly for not having one and some adamantly for deciding later".
Hague also noted that Lord Wood, one of Ed Miliband's top advisers, had said it was "conceivable" that Labour would decide before the 2015 election to back a referendum.
Lord Wood made the comments in an interview with The Huffington Post UK. "We’re going make a judgement whether to have a referendum," he said. Asked if Labour would make such a pledge in its manifesto, Wood said: "It’s conceivable because we are going to make up our minds before the next election."
Several of the Labour MPs who did rise to speak during the debate were those who favour a referendum on the EU - including the chairman of the home affairs committee Keith Vaz, veteran Labour MP Dennis Skinner and eurosceptic Labour MP Kate Hoey.
Hoey, who said Miliband's order that his MPs abstain on the vote did not make sense and that she would be voting in favour.
"I genuinely can not understand why we want to abstain, other than saying we are playing into the hands of the Conservatives," she said. "I don't think im playing into the hands of the Conservatives by voting for this, I am playing into the hands of my constituents."