Basic understanding and knowledge if firearms here is almost zero. People hear of a situation like this and the immediate reaction is to 'ban guns'. Statistics show that firearms are used in very few violent crimes here.
Knives on the other hand are the preferred weapon of choice for thugs, rapists, robbers, chavs, etc.
"Police figures show that there were 39 firearms-related deaths in 2008-09 and that seven of these involved a shotgun. That total was the lowest recorded by the police in 20 years. Guns play a role in just 0.3% of all recorded crimes - one in every 330 incidents."
A few years back there were a number of murders in South London, involving young people, mostly, but not all, were 16-20 year old black kids as both the killers and the victims. Some of the murders were totally random and indiscriminate. Unfortunately what came out of it was not a debate on violent youth crime or gang violence, but an insatiable desire to further ban guns and also knives. None of the firearms used in the murders were legally owned or registered, thereby making further attempts at gun control a pointless endeavor as it would not have prevented any of the killings from taking place.
I guess this is nothing arcane to the UK as the anti-gun lobby is strong in lots of places as well. What it does though is shift the debate away from the real issue(s) in an attempt to make a proverbial scapegoat out of something else. Even in a society devoid of legal gun ownership events like this will still occur. Crazy people and the criminal element will see to that. What needs to be improved upon is the management of the situation when it happens and making sure the right people are sufficiently empowered to deal with a crisis situation.
Oh and for the one eye-witness that claimed he saw a "huge sniper-rifle with a massive scope" - turns out it was a .22 LR and not some .308 Win Mag that was intimated.
http://news.bbc.co.uk/1/hi/england/10220974.stm