Imagine you’re having a barbecue in your back garden. Suddenly, you notice a guy in a van across the street taking photos of your house. That’s a potential domestic threat. MI5 is the agency that handles that guy.
MI5’s official name is the Security Service. Their job is to protect the UK inside its borders. They handle counter-terrorism, espionage on home soil, and subversion. If someone is plotting to bomb a train station in Manchester, MI5 is on the case.
They’re like the undercover security guard at your local mall. You never see them, but they’re watching the cameras. They don’t need a fancy passport—they just need to know who’s causing trouble in the neighbourhood.
