For what its worth last year in San Francisco CA (not exactly a hot bed of gun owner rights) a convicted felon shot a person in the home the convicted felon was living and all charges (including being a felon in possession of a firearm. The DA said who dropped the charges said everybody has a right to defend themselves. I do think it this case there was political pressure to drop the charges because the convicted felon was a celebrity in some circles. Don't know anything about the laws regarding self defense in the UK but it sure sounds stupid.