When Ming Campbell called for a referendum, he was talking about a referendum on the question of being “in or out” of Europe – not one on the more specific question of the Reform Treaty (aka Constitution), even though the Lib Dems are-or-were seemingly in favour of a referendum on the treaty itself.
“The Liberal Democrats want an honest debate so they must not try to force people into a false choice between giving even more powers to the EU and leaving altogether. The overwhelming majority of people in Britain want to co-operate in Europe but not give more powers away.”
On Radio 4’s Any Questions a couple of weeks ago, both these questions were put to the audience – admittedly not a rigorously random sample by any means, but from what I remember, a clear majority were in favour of being in Europe, but separately, a clear majority were against the treaty. If we held a referendum only on being in-or-out, and if the majority voted for “in,” it would be easy enough to claim that that would give a mandate for signing the treaty – easy, but wholly inappropriate. We need a referendum on the treaty itself, whether or not we’re also polled on ‘in-or-out’.