Bought a house that's in the London OWL (neighbourhood watch) system but it doesn't have any alarms installed. Can anyone tell me about the basics of alarm systems please? Do they have to be monitored externally (monthly cost of £50 from what I've read) or can you have an alarm installed as a deterrent only? I've want to get the ring doorbell installed but my husband is dead set against it for privacy reasons (he's also against Alexa, etal). Looking for some clarity as I really don't know what I'm looking for and don't want to be ripped off!