Cast iron promises

The old joke (not a funny one, not any more) about how can you tell if a politician is lying (because you can see his lips moving) seems to have popped up in the news today over Cameron's speech about the EU.
Oddly enough he seems to have caught Millipede E out, though not the boy Clegg both of who have gone back to their fallback positions of not saying anything to rock the EU at all.
BBC.

David Cameron has said the British people must "have their say" on Europe as he pledged an in/out referendum if the Conservatives win the election.
The prime minister said he wanted to renegotiate the UK's relationship with the EU, before giving the "simple choice" of a vote on accepting the result of the talks or leaving the EU.
The news was welcomed by eurosceptics who have long campaigned for a vote.
France and Germany both warned the UK could not "cherry pick" EU membership.
During noisy Prime Minister's Questions exchanges in Parliament, Labour leader Ed Miliband said Mr Cameron was "running scared" of the UK Independence Party, whose poll ratings have been rising.
Mr Miliband, who said he opposed holding an in/out referendum, said Mr Cameron "is going to put Britain through years of uncertainty, and take a huge gamble with our economy."

We'll forego all the usual caveats about risk to the economy as in reality a phased withdrawal would leave us in a position to negotiate our position vis the EU in a manner similar to either Switzerland or Norway, both of whom trade equably with the EU, yet have the right to veto any EU proposals thrown at them should they so desire.
Cameron is taking a bit of a gamble here, but with his party increasingly unpopular as well as a limited resurgence to Ukip he's having to go down a path which he clearly is not happy with in order (he hopes) to garner some votes.
However we all know about cast iron Dave's promises, there's a lot of wriggle room in his promise of a referendum, certainly enough to refuse us one if things change such as the EU giving him a new deal.
This plus if anyone thinks the EU will fight fair over any referendum offered means that those of us who oppose our EU membership will have a massive fight on our hands particularly as the government such as it is will probably recommend that we vote to stay in, or at least the likes of Cameron will.
As far as I can see, the only way we'll be offered a referendum is if the government is convinced it's going to remain in.
Otherwise, we simply won't be asked.