living in the past means no future
Great Britain has no discernible culture so Whites, themselves, cannot define Britishness. This is because the Irish, the Scots & the Welsh revere their own cultures far more than that of England, and would wish to politically separate themselves from it.
Most of what Britain thinks is indigenous comes from elsewhere. The religion from the Levant; the Pound, the Law, the Weights & the Measures from Italy; and the Language from south India, Germany & France. The greatest street festival in Europe is Black - the Notting Hill Carnival; meaning Whites do not how to enjoy themselves. The national dish of England is curry (from India); meaning the English do not even like their own food.
For themselves, English Whites have only contributed a simulation of their weather as the basis of their temperament: Cold & Unreliable.
As White culture declines, it will be prone to greater and greater displays of jingoism and national chauvinism to solace them for the death of an Empire that the rest of the world was only too happy to see the back of.