Well the obvious touchpoints to me are that at one point the British Empire controlled about 60% of the world's wealth, was capable of conquering the Indian subcontinent and was a thought leader to the justifiably-named "Age of Enlightenment" that was the approximate foundation of the modern system of global organisation (let me just invoke Newton, Bacon, Locke and Adam Smith because they are good names to remember).

The UK today is world leading in a few industries. Which is underselling it a bit because I suspect even North Korea is world leading in something. The UK have a bit of wealth left over from the empire and some traditions they can be proud of in amongst a sea of fairly average policies and people. Still a nice place to live if you can handle the weather. Not really a leader, more a US follower.