Explore the alternative view, listen to people, try to see it from a different perspective ... Why don't you start with yourself?
Just a thought...
As for the UK population, they are not rejecting the idea firsthand out of ignorance, they have been living with it for 20y, this is how they formed their opinion, it's not coming out of thin air or biases, it's not a theoretical discussion, it's their direct experience.
Your pov has been the mantra for most of these years, you have had your fair chance to expose your views, win people over, let facts speak for themselves, etc. And yet, people don't like it as much as you would like them to. It is not a question of needing more time or doing more to convince, it is a question of you not accepting you have lost this debate. That's the denial.