Definitely later than the 70s, in 1987 Roderick Newall killed his parents, that was a very famous case. Then there was the Portuguese man who killed his two children and himself. Those aside, murders are very rare here, in fact most crime is rare other than drugs and alcohol-related public disorder when pubs and clubs close. Our population is about 91,000. One doesn't hear of people with knives, prostitution, muggings, it is just a safe place to live. When we get vandalism, which does happen from time to time, we get incensed.
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Many a child has been spoiled because you can't spank a Grandma!