>where handguns are entirely illegal

Handguns aren't entirely illegal in the UK. If I'm not mistaken then, roughly speaking, what the law prohibits is rifles below a certain size. In the UK it is possible, for example, to legally own long-barrelled pistols and old flintlock pistols. Another caveat is that the ban doesn't apply in Northern Ireland.

I don't think this really detracts from your point at all.