It can be argued - and has been by a number of folk - that in passing the legislation that initiated the referendum, Parliament returned the primacy from themselves to the public.
Then that would be in error. Parliament enacted the referendum as advisory only, thereby retaining their primacy. They didn't have to - they could have made the referendum binding, as was the case for the AV vs FPTP referendum. They chose not to and therefore primacy remains with parliament.
This is the actual wording on the official parliamentary briefing paper on the bill on the subject:
'This Bill requires a referendum to be held on the question of the UK’s continued membership of the European Union (EU) before the end of 2017. It does not contain any requirement for the UK Government to implement the results of the referendum, nor set a time limit by which a vote to leave the EU should be implemented. Instead, this is a type of referendum known as pre-legislative or consultative, which enables the electorate to voice an opinion which then influences the Government in its policy decisions. The referendums held in Scotland, Wales and Northern Ireland in 1997 and 1998 are examples of this type, where opinion was tested before legislation was introduced. The UK does not have constitutional provisions which would require the results of a referendum to be implemented, unlike, for example, the Republic of Ireland, where the circumstances in which a binding referendum should be held are set out in its constitution.'