My son and daughter-in-law were with us at the time, my phone went off at 2:58pm (Utility Warehouse on EE network), my son's went off about 2 hours later (Giff-Gaff). Neither of my wife's (Three) or daughter-in-law's (can't remember her network, probably Three) phones went off at all. Was this project managed by Dido Harding by any chance? Edit; Ignore the last daft comment, it was way too successful for her to have been involved with....
I'm on Smarty (Three) and my fiancee is with Three... both of ours were triggered at just before 1510.
It doesn't work anyway. Apparently two missiles landed in Oakwell tonight and the only alert I got was a bloke on the pa system 5 minutes later