Warning; Bill, don't read this. It'll only depress you...
Jaeger wrote -
"Recently a a man in England was convicted of murder because he shot and killed a home invader. The homeowner's shotgun was reported to be illegally owned. If our laws ever reach that point I will no longer be a lawman."
Essentially correct.
The homeowner was an elderly farmer. His house had previously been robbed about a dozen times (I can't remember the exact figure, but he was definitely being targeted by the local thieves) His gun was illegally owned, of course, in the UK.
IIRC, three men invaded his home and threatened him. He produced the gun and told them to go away. They ignored the warning and he fired (he maintains) in self defence.
He was convicted of murder. Given his age and state of health, it's 99% certain he'll die in jail.
I don't think the prosecution sought to deny that the intruders threatened him, or that he believed his life was in danger when he opened fire.
The Martin case confirms what they taught me at law school 14 years ago; in British law, in real terms, there is no right of self defence. You're supposed to hold still while the bad guy scrags you, and leave 'justice' to the police.