In Winston Churchill’s famous 1943 speech at Harvard University on the common ties of the English-speaking peoples, he defined the bond in terms of three main things: law, language, and literature. Indeed, when he elaborated on what he meant, he spoke mainly of concepts derived from and guaranteed by English law:

Law, language, literature—these are considerable factors. Common conceptions of what is right and decent, a marked regard for fair play, especially to the weak and poor, a stern sentiment of impartial justice, and above all a love of personal freedom . . . these are the common conceptions on both sides of the ocean among the English-speaking peoples.

Moreover, these legally derived cultural values were not only appreciated by those people of direct British descent: They were transportable to other countries.

As a man with direct personal experience of imperial rule in the...