A 73-year-old man approached Sweden's crown princess at a public event at the Citadel castle in May, intending to invite her for a cider. It sounds like a harmless scene from a country whose royal family prides itself on being accessible to everyone. Then security opened his backpack.

Inside they found two knives. He was carrying a third in his pocket. Plus illegal substances. According to reports, what drew their attention was the way he spoke - officers noticed he was losing the thread of his own stories, so they decided to check. That is all that separated a ceremony from something else entirely.

The defence everybody tries

The man claimed the knives were for repairing an engine and that he did not know there was a law on carrying weapons. He is not the first to try that sentence and he will not be the last. The court in Lund is now prosecuting him for breaching the law on prohibited items and for illegal substances. A records check turned up previous convictions for petty theft and traffic offences.

No authority has confirmed the man intended to harm Victoria. He neither admits nor denies. But the question that remains is not about his intent, it is about the system: how close can someone get with three knives in a backpack before anyone thinks to open that backpack?

The price of accessibility

The Scandinavian monarchies have spent decades building an image of normality - kings on bicycles, crown princesses queuing like everyone else. It is a lovely story and partly a true one. But every such event is also an open door, and a door cannot tell the difference between a man who wants to buy you a cider and a man carrying something else.

The most uncomfortable part of this story is that the system worked only because somebody noticed odd behaviour, not because a procedure existed. That is not security, it is luck in uniform. And luck does not repeat itself on schedule.