A promise to have an EU referendum was included in the manifestos of all the major political parties at the time. Tony Blair promised a referendum, but, under Gordon Brown, it was dropped. One of the reasons was that the Dutch had had a referendum and responded negatively so, even then, there were concerns that the result would be a 'no' vote. Shortly after, the Treaty of Lisbon was ratified - without public consultation in the UK. Eire held a referendum and, when the public voted against it, the EU jiggled it around a bit (making no substantial changes) and made them vote again to give the 'right' answer.
FWIW, I feel that, if we had had a referendum then, pre the financial crash, it would have been much better, whatever the result was.
What many Leavers object to, I believe, is the total lack of public consultation in the evolution of the EU.