One way of thinking about it, the success of the elite (meaning the aristocracy) may be separate from the success of the empire. Most of the work behind the latter was done by the industrial bourgeoisie, engineers, workers, colonized people, etc., so the question is, how big a direct impact did the elite have on the empire? How successful they were individually is a different question.

They had a more technologically advanced society than anyone else at the time, which enabled their empire building.

The Industrial Revolution started in England, which gave them a technological leg up on everyone else, somewhat like playing a strategy game where you get to unlock certain techs before everyone else. If you have factories producing steamships while your opponents are still building sailboats by hand, you're probably going to win a naval conflict, which you can then use to start a colony.