Gun control has a profound effect on homicide rates, which is the central aim. General violence and crime are a different matter.
Not for London. Perhaps you are referring to other data?
Guns make it very easy to kill even if there isn't a specific intent to do so
They also make it much, much easier to an intended victim to defend themselves. Therein lies the rub.
whereas with manual weapons there usually has to be a thorough attempt. With that being the case, most all homicide that occurs under strict gun control is purely intentional.
As opposed to accidental death and/or suicide? I'm not too concerned about suicide as someone who intends to kill themselves will find a way if they are convinced they want to go through with it.
Accidental death, while tragic, can be prevented if the gun owner takes necessary precaution such as trigger locks, gun safes and gun safety training.
Just like with an automobile, we cannot remove human error from the equation completely.
America's problem with guns is that it's current laws make it easy for a criminal to become a murderer simply by reacting in fear with a pistol which is a how a majority of gun homicide goes down. You only hear about the really malicious incidences that occur and that misleads people into seeing the problem differently.
The issue with the US, I believe, is the level of gun saturation. Criminals can get them all too easy. Therefore, law abiding citizens should certainly be able to also own one. How many guns used in homicides in Chicago (for example) are legally obtained?