From his restaurant at an old Nazi military bunker on Jersey’s rocky northwest coast, former fisherman Sean Faulkner makes a prediction: "If they don’t get their own way, they’ll be back.”

Like his fellow islanders, Faulkner, 66, had just watched French fishing vessels stage a protest over changes in access to waters following the U.K.’s departure from the European Union. The standoff prompted Britain and France to deploy warships in the strip of sea that separates them. Billed as a game of chicken by U.K. tabloids, the same press rejoiced when the French went home.

So while the immediate danger was defused, the sight of a naval confrontation near an island of 100,000 inhabitants was a reminder of the real-life consequences of an acrimonious divorce and why it’s such populist political catnip.