Terribull
We all know it's just one of those terms/words that the left use to try and belittle , usually when feeling aggrieved that the debate /discussion is challenging their view in a more sensible manner. It's similar to the same old, same old tactic when debate/discussion is not going their way Thatcher, Right Wing Press and Colonialism is rattled out.
Your post of 10.41 was very good but obviously that is my opinion and others will not agree.
I will add that I am not sure there is a large number of the public who still believe we live in an 'Emperical Dream World' and see Great Britain as the 'Centre of the Universe'. Most people take a more realistic view of life and simply get on with living for today and consider those terms to be historic. In fact the younger generation would probably look at you blank wondering what you are on about and what does it have to do with this century, what does it mean for them .
The UK has simply evolved as the world , to use a crazy term, got smaller. The OP is a fair question but pointedly is aligning the question with defence spending and are we now a small, insignificant country that should stop seeing ourselves as the worlds police force and should we spend on nuclear weapons. So to answer that point the United Kingdom is a member of NATO, the UK is a member of the United Nations , the UK is a member of the G7, G20 so it naturally follows that the UK is small in land mass but the UK is not an Empire but it certainly is a country that has earnt respect worldwide and that is relevant for the 21st Century.