It's an interesting and worrying topic this.
If everyone had alarms, and cameras, then the number of burglaries probably wouldn't go down, it would just set the bar higher for home security (expense), which would basically just force the buggers to take more risk (which they would, as they see this "line of work" as their only option).
Nobody cares about alarms or cameras, and you've got zero chance of the police turning up as something is ongoing, or having the resources to be able to do something about it after the event. People in the USA still get robbed, and burglars are well aware that homeowners are likely to have guns, but it doesn't scare them, or not enough to not do it anyway.
Best chance would be making the doors and windows as secure as possible, but the cost outlay on this is probably not worth the risk reduction (especially if everything is insured/ replaceable), and they will still get in if they want to, it just might take them 20 seconds longer. Or they don't get in, and now you have to replace your £2,000 back door.
Neighbourhood watch schemes will work, to some degree, but realistically, even if someone sees a burglary ongoing, what are they going to do? Ring the police at best? The chance of someone going over and taking matters in their own hands, to protect your stuff is slim, and they are not likely to increase their own risk.
Sad state of affairs, but that's what happens with a lack of police and a weak justice system.
