Was the EEC created to set up free trade?

Certainly the referendum in the UK in 1975, referred to the EEC as 'The Common Market'.

The actual Wording of the referendum was:

"Do you think the UK should stay in the European Community (Common Market)?"

The vast majority of those who voted in favour (including me) believed that membership of the Common Market related solely to trade. It would be interesting to know how they would have voted if they had known what the EEC would become.