Isn’t it just as likely that Britain will hit the rocks and break up?

Imagine popular rage, therefore, when it was discovered that he escaped aboard lifeboat No 1 with the women and children — and it was whispered that he and his wife had even bribed the crew not to rescue victims in the water, in case the boat should be swamped. As it was, this hateful calumny was later disproved; and Duff Gordon’s defenders made an important point about his basically wretched behaviour. It was true that he was one of a small percentage of men to survive, and it was true that lifeboat No 1 carried — incredibly — just 12 people, when later boats were full to bursting of terrified human beings. But the reason his lifeboat was so comparatively empty was that when it was launched, so many people on board Titanic still shared the optimism of the Costa Concordia waiters.

They believed the newspaper claims that Titanic was unsinkable, and you can see their point. It must have seemed utterly incredible that a gigantic steel vessel, in a flat calm, on a well-known route, could come a cropper on a piece of frozen water. And to the cruise ship waiters this weekend, it must have seemed even more incredible that their floating village — twice as populous as Titanic — could just flop on its side within sight of Tuscany.

Millions of people take these cruises every year, including 1.7 million Britons, and the boats are one of the safest means of transport on earth; and as they felt that first crunch and tremor in the hull, it is no surprise that they defied the evidence of their senses and continued to scoop up the olives and the breadsticks as they rained off the tables. They were in the grip of denial, a denial based on the fallacious and complacent inductive logic that because things have been all right so far, they are going to continue to be all right — and as with the good ship Concordia, so with the ship of state.

It is now more than 300 years since that saucy and magnificent vessel, HMS Great Britain, has sailed the seven seas, and for those of us who have been aboard all our lives, it still seems out of the question that she could really hit the rocks and break up. Britain is a giant fact, one of the world’s most successful political unions, that has produced everything from an empire to a broadcasting corporation to a particularly nasty type of sherry. I am like the Concordia waiters, in that I can’t really believe, somehow, that we can be set on a course for destruction.

But look at the facts, my friends. Look at that submerged reef marked “devo max”, or fiscal independence for Scotland. If you can unpick the fiscal union, what is there to maintain the monetary union? And if you unpick monetary union — as George Osborne rightly points out — then political union is dead. The Coalition Government is like the chap in the crow’s nest of the Titanic (his name was Frederick Fleet) who strained his eyes into the night at 11.40pm and then cried, in a stammering howl: “Iceberg, right ahead!” I don’t know if there is time to avoid a rupture.

As things stand, the polls suggest the people of Scotland are too wise to go for full independence; and, as I say, no one currently believes in their bones that it will really happen. But then, the waiters of the Costa Concordia couldn’t understand how their colossal ship — the biggest ever built in Italy — could founder in such humiliating circumstances, and the unsinkable Titanic lies broken in two at the bottom of the sea. That is the nature of slo-mo disasters: they can change very quickly, from being an outlandish theoretical possibility to a predestined inevitability.