I decided to turn mine back on for the test, mainly because I have a friend who is not confident with his phone so I wanted to be sure I could tell him how to get rid of it if he didn't work it out himself. Mine went off at 3pm promptly, was on the way to the corner shop and could hear others' phones shrieking as well, quickly swiped it away. My friend then texted - not sure if he had got rid of it or not. I said he must have done, otherwise he wouldn't be able to text me
Have now turned it off again, been reading about these emergency alert systems across the world and there have been a number of false alarms, terrifying people unnecessarily. It seems not all phones got the alert, some issue with the Three network as well as possibly not keeping the operating system up to date. Only 4g and 5g phones could get it in the first place anyway, no 3g or non smart phones. Judging by the comments on the Telegraph website, it was not a massive success - lots of people never got the alert, even if their phone was capable of it.