Can luggage left loose on a back seat be dangerous under Northern Ireland driving rules?

Yes. The Highway Code instructs drivers to secure loads and luggage safely.

In a collision or sudden stop, an unsecured suitcase, toolbox or heavy bag can strike an occupant. Stow heavier items low and within the boot where possible. If using a roof box or trailer, follow the manufacturer’s load limits and make sure every item is secured against movement.