In truth, what has Gemma O’Doherty exposed?

In the time of Trump, narrative is everything. Facts are a secondary consideration. The US president, for instance, need only tweet and his supporters believe what they read, irrespective of any conflict with the facts.
So it went also with Brexit. The narrative was that the UK would be free to prosper on its own, and money would be saved to pump into its own services. All the facts suggested otherwise, but people heard what they wanted to hear, and didn’t bother too much about the facts.