It kicked off with the "concessions" David Cameron claimed to have negotiated with the EU on free movement of people.
These were fairly underwhelming, and many voters resented his attempts to pretend otherwise.
Then we had the classic error of insulting and maligning the voters. Remain campaigners continually referred to people who were considering voting Leave as "Little Englanders" – and sometimes worse. Insulting the voters is simply the best strategy to drive them away.
Remain also lost the battle of the top-line message.
The Leave campaign offered the simple yet powerful, "Take back control". But Remain’s uninspiring "Stronger, safer and better off" tried to be three messages in one, which rarely works, and didn’t, in any case, reflect the thrust of the Remain campaign.
And the reaction to the tragic murder of Jo Cox was misguided, leading to the unedifying sight of some Remain campaigners, such as Stephen Kinnock, appearing to use her death for political ends, which alienated many people on both sides of the argument.
Now, some of the most high-profile Remainers in the land (such as Tony Blair, Nick Clegg and Michael Heseltine) are leading the charge to encourage the voters to think again, and to accept a second referendum.
Can they be successful?
The odds are stacked against them, not least because the official position of both the Conservatives and Labour is to move forward with Brexit, and those two parties won more than 80 per cent of the vote at the general election.
But if they are to be successful, this is what they must do:
1. Focus on the opportunities the EU provides for more widespread prosperity and greater security in a world which is increasingly volatile and dangerous. All too often in 2016, Remain sought to spread only fear at the dangers of leaving, rather than pride and excitement at the possibilities of staying.
2. Never again make the mistake of underestimating people’s belief in national sovereignty. Notwithstanding point 1, the lesson of 2016 is that sovereignty trumps money.
3. Publicly accept the validity of people’s concerns about the massive increase in population since 2000. Too often, Remainers have written off such concerns as being the result of bigotry and racism, which has merely served to offend Leave voters and to strengthen their determination.
4. Campaign for a new and meaningful settlement on free movement of people – the kind of settlement that EU leaders denied David Cameron in early 2016, and which should address Leave voters’ concerns.
5. Keep Tony Blair out of it. For all his abilities as an outstanding communicator, he is now, according to Opinium, by far the least trusted of all public figures on Brexit.
However unpalatable Brexit is to many, it is undeniably the democratic will of the British people.
So any new referendum must be held on the basis of Britain having a radically different type of EU membership.
A mere re-run of the 2016 referendum, to give voters a second chance to make "the right decision", would undermine democracy.
It could even lead to a yet bigger Leave victory next time.
Robert Taylor is a media and comms trainer