Where I lived with my mum (as a youth not a creepy 40yr old virgin type) in Breedon, they have a limestone quarry and they used to use th eold air raid siren before they did any blasting. Its such an eerie sound. As kids we all used to hit the deck at the local primary school.
With the four minute warning issue, I think I'd rather not know. Does beg the question whether or not the government would inform us, or just sneak off somewhere