What is the UK Emergency Alert System and when will we get messages?

Phones and tablets in the UK may unexpectedly make a loud siren sound in April

The UK government’s emergency alert system test will happen on Sunday 23 April.
Phones and Tablets may make a loud siren like sound even if on silent mode

This is just a test to see how it works and if proved succesful it can then be used for any national emergency such as floods or attacks etc.

It could also vibrate, or even read out a message automatically.

The alert will last around ten seconds and you’ll need to tap the message to clear it and carry on using the device

Update

The time is confirmed to be approx 3pm