Vehicles that use blue flashing beacons are primarily emergency and authorized service vehicles. These include:

• Police vehicles, used for responding to crimes, emergencies, and traffic incidents.
• Ambulances, which use blue flashing beacons to indicate urgent medical missions and to request immediate right of way.
• Fire trucks and other fire and rescue vehicles, which use blue flashing beacons during emergency response.
• Search and rescue vehicles, to enhance visibility during critical missions.
• Certain security and law enforcement vehicles during patrols or security operations.
• Some utility and maintenance vehicles, especially during urgent or emergency tasks.
• Coast guard and maritime rescue vessels in some cases.
• Military vehicles during specific operations requiring urgent clearance.
• Civil protection agency vehicles responding to natural disasters or other emergencies.

In general, blue flashing beacons signify that the vehicle is responding to an emergency requiring other drivers to give way safely and promptly. Unauthorized use of blue flashing beacons is typically prohibited by law.

Additionally, some theory test and driving knowledge resources highlight that blue flashing beacons are associated with emergency services like police, bomb disposal, motorway maintenance, and breakdown recovery vehicles in some contexts.

To summarize, blue flashing beacons are used mainly by emergency response vehicles—police, ambulance, fire services, and other authorized emergency or high-priority vehicles.