Dave,
Thank you, BWM, but you need not have. Every single source from the ardently pro-EU lobby to the rabidly anti-EU media have never said it was legally binding. It seems that the only people who did not know that fact are right here on Mudcat

I quoted a Labour and a Conservative MP who stated that MPs voted 6 to 1 for a referendum believing it to be binding.
So not just Mudcatters.
Those Mudcatters who claim they did know are unable to say how they knew.