RUTHFULLY YOURS

‘Bye-bye England,” shouts the Bild. In Der Spiegel, a cartoon shows Prime Minister David Cameron being dropped into a rowboat as the great European liner steams ahead. Headlines in the New York Times and Financial Times agree: Britain is “isolated” from the euro zone. What could make a Briton feel warmer this Yuletide, or more nostalgic?Britain has been warned ever since the European Coal and Steel Community was created by Jean Monnet in the 1950s that if she didn’t get onto the “top table”—sometimes it was “in at the ground floor”—then terrible things would happen. Europe would surge ahead without her.

When Charles de Gaulle repeatedly vetoed Britain’s future membership in the European Economic Community (Common Market), liberal circles in London wrung their hands at our probable fate. When Britain finally joined in 1973, there were further dark warnings that we needed to be a leading player or we would be marginalized, wrecked as a global trading force and so on.

Then Margaret Thatcher came to power and started to use Britain’s veto as a way of getting Britain’s grossly bloated financial contributions to the European Union under control. The United Kingdom was warned anew of dire consequences. The same dire consequences were predicted when Britain failed to sign up for the social charter provisions of the Maastricht Treaty in 1994, in order to maintain some control over its domestic economy from the dirigistes on the Continent.

And when Britain refused to enter the euro zone in 1999, all the clichés were trotted out again—it would lose its seat at the table, miss the train as it left the station, blah, blah, endlessly blah. In retrospect, it turned out to be the best economic decision Britain has made for a century.

On Dec. 9, Mr. Cameron exercised Britain’s veto over the proposed European fiscal union—a fiscal union that included new rules sure to hamstring the U.K.’s financial services industry, which provides over 10% of the country’s gross domestic product.

Anyone with a sense of history knew precisely what to expect. And no single organ of informed, civilized, progressive opinion failed to deliver.

Mr. Cameron has been a friend of mine for over a quarter of a century. He is utterly sound when it comes to protecting British interests in Europe—which is why he wielded his veto when there was no alternative. Britain is the third-largest economy in Europe. Forty-one percent of its trade is with the euro zone, which means 59% isn’t. It can sell bonds on the international markets at interest rates at which Italy, France and other euro zone countries can only dream.

The fact is that Europe has cried wolf yet again, and Britain means to call its bluff yet again.

The mistake that the liberal media constantly make, especially for some reason in America, is assuming that when Britons are isolated in Europe, they are also uncomfortable. Yet since the 16th century it has almost always been precisely when she was most isolated that she was later proved most right. And whereas President Sarcastic—does he have any other form of address when talking to opponents?—is currently the least popular president of France in the history of the Fifth Republic, Mr. Cameron saw his Conservative Party overtake Labour in approval ratings after he exercised the veto.

British Foreign Secretary William Hague has written a superb biography of William Pitt the Younger, whose most famous and effective speech comprised one sentence during the Napoleonic Wars: “England has saved herself by her example and will, I trust, save Europe by her example.” King George VI actually rejoiced after the fall of France, writing in his diary 1940: “Personally, I feel happier that we have no allies to be polite to and pamper.” That is the true voice of Britons, and one that David Cameron has articulated superbly.

Mr. Roberts, a historian, is author most recently of “The Storm of War: A New History of the Second World War” (Harper, 2011).