One of the key economic innovations which allowed Britain to gain supremacy was the development of banking and financial markets.
Britain's reign from 1815 to 1915 has some key points along its route, the first being the social revolutions which swept Europe around 1848, followed by the Crimean War in 1853, by the time the US Federal Government overwhelmed the Southern states who favoured a looser form of federalism in 1865 and German unification was completed in 1871 the end of Britain's reign was assured but the long lingering death took another lifetime to complete.
For this latter half of British assumed sovereignty the British set out to be not only the world's policeman but the guardian of its morals; the enlightenment of Africa bringing could Christian values and western society to the dark heart of Africa, India and seeing the end of the Chinese Imperial system.
Through the 1960's waves of social revolt swept the Western world; civil rights, student protests for a while the stability of the West seemed threatened and the ruling elites turned to the same solution that had been employed in 1848... the extension of the franchise.
This period culminated in the Vietnam war, a war which bankrupted the United States much as the Crimean war (and the two invasions of Afghanistan) exposed the weakness of the British.
Both Russia and China have undergone social reformations since then and the European Union is changing into something, what it's final design will be remains as yet uncertain, but it is definitely changing.
The US presidential elections has exposed the American belief in their own supremacy as a people who believe they hold a solemn mission to tell everyone else what to do, engaged in wars throughout the Muslim world and now staging 'war-games' with Japan in the East China Sea and backing the Philippines in their ongoing showdowns with Chinese naval vessels in the South China Sea.
So I guess that puts us at about 1895 in the British cycle, just before the Second Boer War with Dr. Jameson about to launch an attack on the gold fields of Johannesburg...