Even on old metal detectors there is a requirement with M&S to have an alarm if the bin is left open. I'd like to not spend a fortune and reckon we can retrofit something but it occurred to me that it would be great if we had a padlock which alarmed after it had been opened for about 20 seconds.
Alarm padlocks do exist but not for if you're using the key. I was wondering how other people had got round this? Any cunning ideas?