Also, a couple notes:
a) Comparing British and American murder rates is useless, meaningless. There is no ceteris paribus here, so there’s no way to assign causation. All you have is random facts and connecting those facts in any particular way, asbent some kind of methodology that can tease out causation, is just demagoguery.
b) The “gun murder rate” is particularly meaningless. Gun murders are no worse than knife murders or head-smashed-on-the-concrete murders. Murder is the problem. The unstated supposition is that, by reducing gun murders, we can reduce overall murder. However, this assumes the point in (a) - that restricting gun ownership will, in fact, lower the violent crime rate. When combined with the observations that AJ made - lower violent crime rates in more heavily armed parts of the US vis-a-vis less armed parts of the US, and lower overall violent crime rate in the US than in Britain - it is easy to see that this entire line of argument is a non-starter.
@JJ: I think the talking-heads would want to take the ratio between the two rates, not their absolute difference. But as I note above, it is all meaningless junk.
Clayton -