So what you're saying MaisieD, is to always take with a pinch of salt anything a politician tells you either in their manifesto or in government.
That, nellie is what 40+ years of enfranchisement has taught me. Few politicians in power tell anything but their version of 'the truth'. With a lot of spin on it.
That 'once in a lifetime vote' nonsense was just a rhetorical flourish. In truth, Cameron must have known that he absolutely couldn't commit the country to it as a parliament (even though it wasn't even 'parliament' that said it!) cannot bind its successors. Which means that anything done in one parliament can be completely overturned by the next one.
Cameron should also have known that he was not constitutionally able to make such a promise; it was not in his power to make it without the approval of parliament.
For my information on the referendum I didn't bother with the politicians. I preferred to see what the experts had to say.
And, before any Leaver says that the experts were mostly Remainers so of course they would be pro-EU, I'd point out that they were pro_EU because they were experts and knew just how the EU and the rest of the world 'works'.