I wonder if the Libya fiasco is playing into that poll. Even the most gun-ho patriot is starting to see Cameron's naive folly for what it is
Doubtful - foreign affairs rarely intrude on the public consciousness when it comes to voting intentions, unless there is a genuinely patriotic war (the Falklands for instance) or a complete disaster (Suez for instance - but even after that fiasco, the Tories got back in - admittedly with a different leader).
Besides, Libya is not a "fiasco" yet - imagine the furore if Gaddafi had actually taken Benghazi and slaughtered thousands in revenge - the real western culprit over Libya has been Obama who has been resolutely irresolute on the topic.