Exactly - so we should disregard the original referendum (a mere poll, as you put it) on the basis of which the British government signed up in 1975 to what was then the embryo EU - though only those experienced in deciphering subtexts in official documents really understood at that time that federation was the real goal not merely the establishment of a free trade area.

> the original referendum (a mere poll, as you put it) on the basis of which the British government signed up

You seem to be trying a reductio ad absurdum argument here and failing.

The UK joined the EEC in 1973, without a referendum but based on an act of Parliament. In 1975 they held an explicitly non-binding referendum that supported staying in the EEC. In other words, that referendum voted to maintain the status quo. You can "disregard" it if you wish, but that would also just mean maintaining the status quo.

The UK has never held a binding referendum on EEC/EU membership. According to the UK's crufty "constitution", this means Parliament gets to decide. If Parliament does nothing, the UK remains in the EU.

The court also relied somewhat heavily on a more specific feature of UK constitutional principles: that if Parliament has granted a right to British citizens, only Parliament itself may revoke it. The European Communities Act 1972, the court held here, has the effect of granting certain individual rights to British citizens (such as a right of appeal to various EU courts). As these were granted by an Act of Parliament, they can only be revoked by another Act of Parliament, not by a decree of the Government. Therefore the European Communities Act 1972 must be properly repealed by Parliament, not de-facto rendered inoperative by action of the Government.