I have no opinion on that. But I can certainly say that clinging on to "The Days of Empire" makes the UK look deluded, stupid, and frankly nasty, and trying to reassert that position in the future looks laughable - even more so given the decision to leave the EU.
Who, exactly, is looking to the UK to take more "leadership"? (that's not a question directed at you, Paul

)
Usually world leaders give things to those 'below' them, like technology, fabricated structures (houses or components to make factories and their fixtures and fittings) etc, that's what makes them, you know, leaders.
Not a criticism of you or your post, but if we are to be world leaders, what have we to give to the world?
We've already given them our railways, energy and infrastructure construction, we make next to nothing that can be identifiably British, the things that we do make are under a foreign brand (Nissan, Honda etc)
We're not even world leaders in the worlds biggest spectator sport, or we'd have at least been in the world cup final a few times (how many English players play football abroad compared to the foreigners who play here?)
The UK leads the world in nothing but making money for a select group of already rich people, doesn't know how (and sometimes want) to tax its people and the companies that live and work here properly, say they want to make work pay, but can't find the jobs that do so (even if there is a surplus of jobs) and yet has a selection of the population who continually vote for the most unsuitable representatives who will never make their lives better or listen to their concerns