At around 3pm, mobiles connected to 4G and 5G networks throughout Britain vibrated and sounded for about 10 seconds in the second test of the system.

Millions of UK phones to sound siren in national emergency alert test, part of government resilience efforts.

Devices will vibrate and make a siren sound for 10 seconds at 3pm, with message confirming alert is a test

It marks the second test of the national emergency alert system after the first in 2023