I think maybe dismantling the empire was a mistake. I mean, by yourselves, you may not be very much... but if you had Ireland, Canada, New Zealand, and Australia back and you all operated as one nation, then you'd be a lot more.
I mean, I really don't think people thought independence through. How exactly are all those countries better off as minor world powers apart, than one larger world power together? It made more sense than the EU, which forced together nations with different languages that don't even have a remotely similar culture.
The only former colony that's actually strong is the US, and I swear that's only because we control over 1/3rd of North America all by ourselves. Probably the best land, too. Most of Mexico is too hot and dry, most of Canada is too cold... honestly, we have the best real estate, and a lot more of it. We certainly aren't doing better because we're smarter. I mean, think about it... what do the US, China, and Russia all have in common? Land. Lots of land. Also a large population. If Canada has the ambition, they may emerge as a superpower in the future as well, because it's easier to develop and use land in colder climates now. A lot of untapped potential there.
Now, I would say that Great Britain's greatest asset is experience and leadership. The problem is that you don't have anyone left to lead, or any place to apply the centuries of geopolitical experience now. You're a nation of generals and kings, but without an army or anyone to lead. Canada and Australia have the opposite problem... they're just sort of being carried along by inertia, not really pushing very hard or trying anything ambitious. They're getting by, but they're not doing as well as they would with your leadership.
I think you allowed political correctness to get the better of you. You have no where to expand in Europe. You're just an island, and if you want to have any real power, you need land, people, and resources. You understood that once, but it seems like you've forgotten or just somehow lost the will to succeed. You don't want blood on your hands any more, you just stay on your island rather than actually doing something about it. Like conquering Africa, trying to go to space and terraform planets... just something to get out in the world and accomplish things.
Because honestly, the truth is, we live in a world where you either colonise and conquer, or become the colonised and conquered. There is no prize for wringing your hands with guilt and feeling bad about spilling blood. It just makes you an easy target for those who would take advantage.
If you ever want to be great again, then you have to work out some way of acquiring more territory, and people to make it profitable. It really is that simple, when you cut away all the philosophical, moral, and emotional elements. Those are the things that matter. Trade relationships are great, higher education is great, diplomacy is great, but it can't replace sheer numbers, large territories, active development, the implied threat of a large and skilled army, and the tax base that comes with all of that. It just can't.
Maybe you've resigned yourselves, maybe you haven't. This is just something that deserves consideration.