We know Ted Heath signed up to 'Ever closer union' - it's the reason some of us were against it from the start. But at the time we joined the EEC, free movement wasn't a legal requirement, many of the countries that are now part of the EU weren't members, and we didn't know just how fast and how far the EU would make member nations subservient to its own bureaucratic rule.Freedom of movement of people has been a goal of the European Community since its inception.
https://en.wikipedia.org/wiki/Freedom_of_movement_for_workers_in_the_European_Union:
Yes, that has been expanded, but at the time of the UK's accession to the EEC in 1973 and at the time of the previous referendum in 1975, you knew that would happen.
Anyway now we do know, so at the first chance we got, we wisely voted to leave before it gets even worse.