Not at all, just very very strict gun laws.
I'm no expert, but here's my take on it... There were two spree killings in the 80's and 90's and the government response was to introduce a ban of some long weapons, and finally all pistols over .22
Because of the terrorist problem in Northern Ireland, we had strict gun control even before these shootings, so I guess they didn't see the need to apply the pistol law?
Here in NI, even a low powered air rifle has to be applied for, and entered on a firearms licence.