One of my favorite examples of this:
I always liked those “Trespassers will be Eaten” signs, myself. And shouldn’t Beware of Doug be part of this discussion?
No worries - it’s an interesting thread!
Certainly I completely disagree with the premise that anyone can make up their own rules and then kill people legally.
‘Give me the money or I will kill you, as previously published.’
‘You are black, which carries a death sentence on my website, so I can legally kill you.’
Here’s a legal discussion site on confronting burglars:
"To show self-defence you must:
show that you reasonably fear immediate attack.
show that you had no alternative avenue of escaping the attack. If you can, you must run away.
your response must be proportionate to the threat. If someone threatens you with a balloon, you may not respond with a knife. If your own life is not under threat you cannot threaten somebody else’s life."
Note point two above. Putting up threatening signs, having a gun and confronting the intruder are all not ‘self-defence’.
The same site has this (although they comment it may be outdated):
“Whosoever shall set or place, or cause to be set or placed, any spring gun, man trap, or other engine calculated to destroy human life or inflict grievous bodily harm, with the intent that the same or whereby the same may destroy or inflict grievous bodily harm upon a trespasser or other person coming in contact therewith, shall be guilty of a misdemeanor, and being convicted thereof shall be liable … to be kept in penal servitude”
I’d definitely dispute the assertion on that site that ‘you must run away’ - proof that getting legal advice off the internet is a poor choice. If you are in your own home there is no ‘duty’ to retreat from a threat - you might be running away into one outside.
But you may not shoot merely to compel someone to leave - or rather, punish them for not leaving. Force, including and up to deadly force, must be facing a genuine fear (whether well-founded or no) of immediate death or serious injury.
English courts tend to deal harshly with those who use firearms in violence, whether ‘morally’ justified or not. As the law professor would say, “I do not want to hear about your feelings. I want to hear your reasoned conclusions.”
It’s also a poor choice (and rather rude) to present statements without a cite. 
IANAL, and I’m not going to even try to get into the nitpicky details of all of the scenarios involved for fear of giving anyone bad legal non-advice, but Texas is not such a jurisdiction. In Texas, there definitely are cases where you can shoot to protect property even if your life is not in danger (I have a handbook here with lots of details that they give you at TX CHL classes). On notable example (there are other unrelated circumstances too) is night-time arson suspicion. As related to me by the DPS officer explaining, the arson clauses boil down to, in practical terms you can paraphrase it as “if you see a stranger on your property after dark holding a gas can, it’s legal to fire on them on the assumption they are comitting arson”.
However, I stress that one should really read the Texas laws for themselves before deciding on any hypothetical courses of action.
– Brandon
I’ve always been under the impression that the “defense of property” laws here in Texas have their roots in the Old Republic and the need to dispense summary justice to horse thieves and cattle rustlers when the nearest law might be an hour away by horse. The attitude of the police as portrayed by the media here seems to be one of commendation laced with the official stern warning not to try this at home. I’m sure off-camera most of them would be in favor of giving a home invader or carjacker both barrels – I know I would.
Our home is pretty secure: deadbolts, padlocks, and even a cypherlock. We live in a good neighborhood, with good, responsible people as neighbors. We have two small children, though, and as safe as I feel (or perhaps because of how safe I think we should be), I would do anything I thought necessary to protect my family from an unauthorized intruder.
Fortunately, in most cases, the laws (and The Law as well) in Texas would back me up.
licenced shot gun?
Who (where) requires this?
The OP’s in Scotland; are the laws there significantly different to those in England and Wales with regards to firearms and intruders?
No significant difference