While there is an emerging discussion among a minority of pro-Europeans about the potential value of a referendum, many were very sceptical that it could "settle the question" for any time at all. Might Eurosceptics advance this issue with their pro-European opponents if they could promise that the 'in or out' question would not be put again for, say, twenty years?, I asked Reckless, who is a vocal advocate of Britain leaving the EU.
"At least [twenty years]. Perhaps it would be more like fifty years", said Reckless, arguing that the strongest case for a referendum was that nobody under the age of 54 had the chance to vote in a referendum, last held 35 years ago in 1975.
"The implication is that you wouldn't accept the result. That's wrong. You would have to accept the result", he said. The experience of Norway and Switzerland was that - even if politicians wanted to reopen the issue - the public would take the view that you've asked us, so don't ask us again, he said.
The idea of an in/out referendum was discussed by several speakers, having become a talking point in the EU debate after Shadow Europe Minister Wayne David said that Labour's policy review would address the question at a Policy Network event the previous week. Speaking at the Fabian conference too, David reiterated that position and also that he was personally unpersuaded - "and so, more importantly, is Ed Miliband" - identifying some of the barriers to the idea.
There are a number of real problems. The issue which is debated and voted on is often not the issue on the ballot paper. Whatever the result, it may not settle the question and it could coarsen the debate. It could becomes a massive distraction from the debate we need to have. We need to talk not just about Europe good or bad, or in or out, but about what kind of Europe the centre-left wants to create.
LibDem peer Shirley Williams, in opening the conference, warned against the idea.
Williams said she had been "deeply furious" when Labour MP John Silkin launched a Labour no movement to overturn the referendum result within just four years of the public vote, managing to put Labour on a pro-withdrawal ticket by 1980, a major issue in Williams and her fellow SDP founders deciding to quit the party.
I was deeply furious. I had gone along with a referendum reluctantly but I did think we would get at least ten years of constructive engagement and influence. Instead, we were right back in the civil wars ... So remember, the referendum is time and again the escape hatch for politicians who can't make up their minds ... It decides nothing in the long-term. In the short-term, you do get a chance to shift the argument. But it doesn't end the argument and it probably never will", she said.
But UKIP MEP Derek Clark, standing in for party leader Nigel Farage who had to withdraw from the event, suggested that whether anything was settled might depend on how close the result was.
If you think you'll win, then OK, do it - and you'd solve the problem for a generation and you'd kick us out of the European Parliament ... But the trouble with a referendum is the margin of victory on one side or the other. There might be a clear result. But if it is 49-51% one way or the other, then the losing side may say that the result does not have legitimacy and they would be right"
Former Tory MEP John Stevens, who left the party over its Eurosceptic stance, said that he had long been sceptical of the use of referenda, but had changed his mind.
"I have come reluctantly to favour an in or out referendum as the only way to settle this", said Stevens.
He predicted a "very rough read" in the next few years, but was confident of a clear victory for EU membership in a referendum.
Reckless argued that the principle of a referendum should trump tactical judgements about which side might win:
"Instead of everybody predicting the result, and working back, we should ask 'Is this the sort of issue we ought to have a referendum about'. But another reason we might have a referendum is if both sides were confident of winning it", he said.
Meanwhile, Stevens predicted that the Cameron government would concede to pressure to hold a referendum on the EU during this Parliament, over Treaty changes rather than the in/out question.
"I predict that we will have a referendum on an EU issue before the end of this Parliament", he said, predicting that "the package on the euro crisis is going to lead to a more substantial Treaty change than most people think ... If that is the case, I think it is going to be extremely difficult for a British government to say 'this is nothing to do with us".
Back on the "in or out" question, Reckless wondered if "there could be a race to be the first party who is pushing it. ... David Cameron has shown on AV that he is willing, in order to gain power, to hold a referendum on something he doesn't believe in", he said, to laughter from the audience.
As I blogged on Saturday, this "in or out" discussion probably somewhat over-estimates the chances of Labour adopting a pro-referendum stance. The leadership is sceptical of the argument. An entirely unscientific show of hands among the largely pro-European Fabian audience (with a smattering of strong 'sceptics) saw a split of about two to one against a referendum, among those attending the final session of the day.
Former Europe Minister Keith Vaz told the House of Commons last month that he favours the move. But probably the most intriguing pro-European advocate of an in or out referendum is Tony Blair's Downing Street Chief of Staff Jonathan Powell, who discusses its potential historic impact in an article (£) for E!Sharp, the European magazine which was (coincidentally) one of our media partners at Saturday's conference.
What Tony Blair did not succeed in doing was winning the British people over to Europe. In his Nobel Peace Prize acceptance speech, David Trimble said that Northern Ireland felt like "a cold house" to its Catholic population. That is the problem for Britain in Europe too. The British feel that Europe is something done to them by the French and Germans rather than something in which they have a shared leadership. If they felt more comfortable, the battle could be won. Euroscepticism in Britain is wide, but it is also shallow. If there were a referendum on :in or out", the sceptics could be beaten.