New Joyce Malcolm book
The point made is that, to the extent we have records, English homicide rates started out high in the 13th-14th centuries, and then fell for the next six centuries. In the early 20th century, England began steadily tightening gun controls, plus criminalizing self-defense, and homicide, gun homicide, and general violent crime rates began to rise, the increase steadily speeding as more controls were added.
Presently, the situation is so crime-friendly that a victim of crime is warned not to shout "help," because that might incite another citizen to (shudder) use violence against the criminal, but to instead shout "call the police." and police are instructed to release a first-offense burglar with a warning.