Until now, I read John Darwin's "Unfinished Empire" and "The Empire Project", "Empire" by Niall Ferguson.
I would like more, but I don't know where to find them with my "filters". I'm not searching for books and authors who give me the bad or good consequences of the Empire, but rather an analysis about how it worked and its place in the world. Pax Britannica, Splendid Isolationism, International Relations as key words.
It's not specifically about the British Empire per se but one of the most pivotal works in colonialism and imperial history is Edward Said's Orientalism. Whether you agree with it or not, its ideas are integral to much modern historiography of empire.