LONDON — Over the centuries, Great Britain spawned the Industrial Revolution and nurtured representative democracy. It ruled the waves and created common law. It nurtured the first antislavery movement and stood up to Hitler.

And now Britain has gone nuts.

To paraphrase Churchill, if the nation should last for 1,000 years, people may look back and say: This was their saddest hour. Actually, never mind: Brexit may cause the United Kingdom to fragment, so that the country might not last a decade more, let alone last a millennium.

The U.K. is headed for a new election on Dec. 12, at a time when both its major parties are headed by people who should never be trusted anywhere near Downing Street. What’s more serious is the likelihood that Prime Minister Boris Johnson may eventually manage to drag a wearied Britain out of the European Union.

It’s baffling for friends of Britain to see Johnson leading in the polls as he recklessly pursues a path that is damaging his country economically and risks dismembering it. Those of us sentimental about the U.K. — Shakespeare! Cream tea! The Beatles! The Famous Five! — feel as if we’re watching a dear friend quaff a few pints of bitter and hurtle toward a cliff.