‘The means by which Providence raises a nation to greatness,” Edmund Burke observed, “are the virtues infused into great men.” How lucky Britons were to have people of the virtues of Burke and Winston Churchill when their country needed them. How desolate that they have no living, modern-day successors in the front rank of politics.

The American Revolution, which Burke supported and Churchill recognized as a cruel necessity, was animated by the cry of “no taxation without representation.” Prime Minister Theresa May’s proposed...