Even if you could conclude that the freedom to own handguns does not in any way influence homicide statistics, you can not then use this as evidence that the UK desperately needs guns to lower the crime rate. If owning guns does not effect pockets of crime in certain states., then that suggests there is no benefit.
To dismiss the idea that the US is different from the UK out of hand is a little unfair. As I tried to suggest before there is a cultural difference. But again, this difference is more useful in a case for Americans keeping guns, and less useful for persuading the Brits they need guns. Yes, there are nations with less rigid gun control and lower crime figures out there. But that still does not prove a cause and effect.