If you’ve never seen an entire platform freeze at the sight of an unattended bag, welcome to London.

Because of decades of public safety campaigns, and a history of IRA bomb threats, Londoners have been trained to treat every abandoned bag like a ticking time bomb. Literally. No one touches it. No one moves it. No one even gets too close.

If you leave a bag behind, even briefly, people will react in the following predictable ways:

• Step away like it’s emitting radioactive waves
• Look around wildly to find the owner
• Notify staff faster than you can say “I just went to buy a sandwich”

I have been on the Piccadilly Line, the tube arriving at Barons Court station going home one evening and a briefcase was noticed to be alone, breaking etiquette, someone asked the carriage if the bag was theirs. No one answering in the affirmative, as the doors opened the briefcase was un-ceremonially thrown onto the platform, the doors closed and we carried on our journey. Barons Court is the first overground station coming from central London going west, just past Earl’s Court.

Tube staff then swoop in like highly trained wizards of public safety. They assess the situation. They ask whose bag it is. They move people away. They handle it with calm professionalism, while everyone else watches from what they believe is a safe distance.

If you need to set your bag down, do it carefully:

• Keep it in front of you
• Keep one hand on it
• Keep it visible

Londoners appreciate this. It tells them you are not leaving a mysterious object for someone else to fret over.

Security awareness is not optional in London, it’s ingrained. But don’t let it scare you. Just be mindful, keep track of your belongings, and remember: no one will ever, ever move your stuff for you. Even if it’s blocking the doors.