Re: Bit late but..,.
"But having said that, the basic idea of having a threshold of votes/majority for any referendum on constitutional change is a very good (essential?) idea."
True. I'll settle for essential.
"Obviously not to trigger never-ending referenda,"
Obvious to you and to me but there seem to be a number here who haven't grasped that the word "second" indicates that no more than two are being proposed.
"Why on earth didn't that idiot Cameron include a similar requirement this time?"
Dunno but possibly either he didn't expect leave to win or, more likely, because it didn't include a binding clause.
One option is for the HoC to debate the petition and come to the conclusion that although the principle behind the proposal is sound there's no need for a second referendum because, as the referendum doesn't bind the government or country to a simple majority, the government can apply the criteria to the existing vote, i.e. the majority wasn't big enough to change the status quo.