Ted,
A point of fact, you CAN land at Heathrow with firearms in your luggage. I landed on 11th January this year with 6 shotguns is locked flight cases and I just went to the Red customs channel and declared them. In this case they were a commercial import so I also had to have a customs broker standing by to do the 'entry' but if they had been my own guns, for sporting purposes, I would only have had to prove I was certified in UK law to possess them and I could have walked.
Thereby hangs the issue, you need to be certified to possess them. Either a UK shotgun/firearms certificate (only available to UK citizens) or a current Visitors Permit is required (the latter costs about $20 and can last for up to a year).
Regarding your later post asking why one wouldn't want one's neighbour owning a handgun? I have had plenty of neighbours who I wouldn't trust with a fly swat let alone a lethal weapon and others who I would have trusted with my life. Surely that is a universal truth and has nothing to do with ones nationality?
