Internet?...1975?....have a word!
So it's alright to say the electorate was gullible and thick back then but not now because the font of all knowledge and beacon of truth, brought to us by Sir Tim Berners-Lee, means it is impossible to fool anyone...ever. Plausible in your universe maybe.
You also forgot to factor in the 40 years of lies and mistruths and sensationalist claptrap about the EU in the media, which I have no doubt coloured the views of all those gullible 1975 voters and their gullible offspring too.
You are a silly billy at times