To continue the crash alarm thread drift, the practice at Valley in the late 70s was to test the tannoy and alarm at midday. This was followed rapidly by the sight of the bridge over the railway line being clogged by administrators, suppliers etc heading off for lunch.
And then came the Royal Visit, when someone realised the test would occur right in the middle of the programme. Answer, test it at 10:00 instead. Result, a Pavlovian response that saw the administrators, suppliers etc. totally confused, milling about trying to go for lunch when they weren’t hungry and when it wasn’t going to be ready for another 2 hrs.