You can't even own airguns which are moderately powerful.
You are incorrect. I've spent 120+ days over there in the last 2 years. One of our customers bought a shotgun during this time period. Background check and he got his paperwork. I went to a gun shop in Rugby, its about 2 hours north of London. Hundreds of firearms. Mostly double barrel shotguns, but rifles too. They hunt deer over there with both. Air guns are now having to be registered and there is a move to register replica, as in non working, firearms. All of this will not decrease gun crime. I was looking for muzzle loader parts, talked with the owners for quite a while. They have lots of business.