Thank you. It's interesting, isn't it, how strongly Anglicanism is bound up with nationalism.
Not entirely sure it is nationalism per se. I think it is tied to groups who are old and socially conservative, and likely politically conservative too. It is more about being backward looking, perceiving some fantasy golden period when everything was great.
I suspect the is also an element of loss of power and control - don't forget that for decades the establishment and elite were conservative Anglicans, and there will have been a perception amongst those in that demographic, even if not themselves elite, that they were part of the group that 'ran things' and made the decisions, which largely aligned with that way of thinking.
Fast forward to today and that elite power block is diminishing, we accept much greater diversity, we don't automatically show defence to the kay establishment blocks (CofE, Monarchy, Conservative party). That must be tough for people brought up in a world where there simply assumed they were part of that ruling establishment.