The UK voters were not given any choice - all three main political parties were gung-ho for Europe and damn the voters.
The politicians just liked to think that the voters weren't interested and were quite content; they were never given the voice to say otherwise.
As I've pointed out a couple of times on NSC, that's just not true. The 1983 Labour Party Manifesto had a commitment to leave the EEC (as it then was). So the voters were given a very clear opportunity to leave if they wanted