but I would say to brexiteers, should there be a third referendum,

1) After Labour won under Harold Wilson, a referendum was held on whether to remain in the Communities after a renegotiation of its membership. The result was in favour of remaining. The European Community were three international organizations that were governed by the same set of institutions. These were the European Coal and Steel Community (ECSC), the European Atomic Energy Community (EAEC or Euratom), and the European Economic Community (EEC)
2)he Maastricht Treaty built upon the Single European Act and the Solemn Declaration on European Union in the creation of the European Union. The treaty was signed on 7 February 1992 and came into force on 1 November 1993. The Union superseded and absorbed the European Communities as one of its three pillars. The first Commission President following the creation of the EU was Jacques Delors, who briefly continued his previous EEC tenure before handing over to Jacques Santer in 1994.
The Community institutions became the institutions of the EU but the roles of the institutions between the pillars are different. The Commission, Parliament and Court of Justice are largely cut out of activities in the second and third pillars, with the Council dominating proceedings. This is reflected in the names of the institutions, the Council is formally the "Council of the European Union" while the Commission is formally the "Commission of the European Communities". This allowed the new areas to be based on intergovernmentalism (unanimous agreement between governments) rather than majority voting and independent institutions according to supranational democracy. after the Treaty of Maastricht, Parliament gained a much bigger role. Maastricht brought in the codecision procedure, which gave it equal legislative power with the Council on Community matters. Hence, with the greater powers of the supranational institutions and the operation of Qualified Majority Voting in the Council, the Community pillar could be described as a far more federal method of decision making.
The Amsterdam Treaty transferred rule making powers for border controls, immigration, asylum and cooperation in civil and commercial law from the Justice and Home Affairs (JHA) pillar to the European Community (JHA was renamed Police and Judicial Co-operation in Criminal Matters (PJCC) as a result). Both Amsterdam and the Treaty of Nice also extended codecision procedure to nearly all policy areas, giving Parliament equal power to the Council in the Community.

In 2002, the Treaty of Paris which established the European Coal and Steel Community (one of the three communities which comprised the European Communities) expired, having reached its 50-year limit (as the first treaty, it was the only one with a limit). No attempt was made to renew its mandate; instead, the Treaty of Nice transferred certain of its elements to the Treaty of Rome and hence its work continued as part of the EEC area of the Community's remit.

The Treaty of Lisbon merged the three pillars and abolished the European Community; with the European Union becoming the Community's legal successor. Only one of the three European Communities still exists and the phrase "European Communities" no longer appears in the treaties.
The European Union has seven principal decision making bodies, its institutions: the European Parliament, the European Council, the Council of the European Union, the European Commission, the Court of Justice of the European Union, the European Central Bank and the European Court of Auditors. Competence in scrutinising and amending legislation is shared between the Council of the European Union and the European Parliament, while executive tasks are performed by the European Commission and in a limited capacity by the European Council (not to be confused with the aforementioned Council of the European Union). The monetary policy of the eurozone is determined by the European Central Bank. The interpretation and the application of EU law and the treaties are ensured by the Court of Justice of the European Union. The EU budget is scrutinised by the European Court of Auditors. There are also a number of ancillary bodies which advise the EU or operate in a specific area.

The United Kingdom European Union membership referendum, 2016, 23 June 2016, 51.9% to leave, turnout 72.2%

The second referendum in the uk was for a very different entity to that voted for under Wilson's government. Primarily as a result of the Maastricht treaty.

Therefore to talk of a possible 3rd referendum is a bit of a misleading, simplistic distortion.
From 1975 to present the EU has morphed from an economic union to an increasingly political union, usurping national identities and rights of self government.