The "Protocols" given to the Irish are worthless. Not one word of the Lisbon Treaty has changed. Every argument for a No vote still stands.
Meanwhile, if David Cameron really is against Lisbon, then he will promise not to ratify it if it has not been ratified on his becoming Prime Minister, with no need of a referendum. He won't, because he isn't. If you want a British referendum, then you just want the matter to be decided over the preceding month by the BBC, as happened in 1975.