The Irish "yes" to the Lisbon Treaty leaves the Conservative leadership at this week's conference in Manchester with a dilemma. This is because their latest pledge for an incoming Tory government - that if all countries had ratified there would be no referendum - is being challenged by Euro-sceptics. David Cameron will be right to resist them: they have done much damage already to the party's international reputation.

The sceptics point to the second sentence in June's Conservative European election manifesto, which states "if the constitution is already in force by then, we have made it clear that in our view political integration in the EU would have gone too far, the treaty would lack democratic legitimacy, and we would not let matters rest there".

The Euro-sceptic...