All fair points, Brian. I wasn't however that anyone should apologize for their past empires, just that I think that the British Empire was not something to we should look back in with pride - you may disagree.
Nationality is largely a matter of where you feel you belong. Although, as you say, e.g. Italy, Germany and the USA have not been around as nations as long as Britain has, most Germans and Americans at least (not sure about Italians) have for a long time thought of themselves primarily , (not exclusively) as such, rather than e.g. as Prussians or Texans.
In my case, I think of myself as primarily as English. The Lake District, the Yorkshire Dales, Stonehenge, Bede, Boniface, Alfred the Great, Becket, the English language, Wycliffe, Chaucer, warm beer, Thomas More, the Church of England, Edmund Campion, Margaret Clitheroe, William Byrd, Shakespeare, Donne, Bunyan, Milton, Purcell, Newton, cricket, football, rugby.... those are the words which press my buttons. Not slave traders, ironmasters, bankers, imperialists, Orangemen, Margaret Thatcher, Tony Blair, invading Iraq, Britpop ...
'Cry God for Harry, Britain and St George !' Doesn't sound right, does it?
But perhaps you think I'm just a sentimental old Tory, Brian.