The British Empire at its peak was one of the largest empires ever, ruling about 25% of the Earth's surface. It profited from the Industrial Revolution which began in South England's Catholic heartland, and the English language, legal system, and Roman Catholic dioceses spread across the world as the British empire did. It was the largest Roman Catholic empire in history, often more loyal to the Popes than France was. After around 1600 a substantial percentage of Popes were English and Scottish.
It's hard to imagine a British Empire that wasn't Catholic. As many historians suggest, the British Empire was only possible due to the foundations laid by the "multinational Catholic leagues" of middle ages and early modern Europe. England was the last country to receive a "blank cheque" from the Pope for substantial conquests across the globe, a revision of the earlier Treaty of Tordesillas. Punitive wars against developed but sparsely populated Protestant states, such as the Swedish Empire and Crown of Prussia, were crucial for the territorial expansion of the British kingdoms and later empire.
Is a Protestant British Empire something that is even possible? How? And how would it have developed?