Britain's main cultural problem is, they over-achieved for a 250 year period and collectively forgot the REST of their history.
For pretty much all of English history, TILL they got hugely lucky at the battle of Gravelines , which is late 1580s, English history has one constant throughout time : Its the ass-end of Europe.
Romans were thoroughly disgusted by the English, given how much more primitive they were than the Gauls.
Throughout the 100 years war for eg, French were the dominant power (england only got to stretch the war out by recruting french traitors like the burgundians and shit), French was even court language of England and cathedral building in england consistently lagged behind france and tried their best to catch up ( which they would by late 1700s).
The Brits forgot, that regardless of how you look at the last 250 years of British history- in highly favourable or negative terms - you cannot ignore the prior 2000+ years history either and maybe, just maybe, that little island off the NW coast of Europe is reverting to its historical norm as a culture group.
While i think this process is inevitable, the British also accelerated this by Brexit, because long term, the best possible way Britain could've continued to buck the trend of British history, would've been to serve as a stepping-stone bridge between Europe and its vast array of cultural descendants, aka North America.
But then again, the average Brit isnt very smart a person and its not past those white supremacist yobs to think that best way to fight 'muh immigration invasion brown people' is to stop being the bridge between the two biggest group of white people- Euros and Murricans.