OC Trainer won't provide proof of anything because he's not in a position to do so. I've read his dozens of posts throughout this thread, and a couple of things are fairly clear through the deliberate fog of his contributions. He has an agenda but is either unwilling to share that (likely) or unable to clarify it (unlikely, as he's plainly adept in the use of our shared language). He routinely uses belittling comments to oppress in preference to informative comments to prove anything. And he really has no valid argument to present against trained private citizens using firearms in their own defence or the defence of others, falling back repeatedly on an obviously flawed and shallow paper from the FBI as though we should all fall on bended knee honouring his wisdom in just knowing about that paper. Oh, and Google, he's really proud of knowing that Google is useful.
The fact is that 90% and more of human beings will react poorly in emergency situations of whatever kind. If there were some sort of test which could be implemented in ways which were acceptable to the populace and yielded accurate results, regarding which of us is likeliest to respond intelligently and effectively when confronted with high stress, dangerous situations, that might provide adequate criteria upon which to base licensing for firearms carry in places like the UK (or Canada for that matter) where generally armed populations are not considered acceptable. Without such a test being available things become somewhat more complicated, and indeed the official statement from the London police which forms the basis for this discussion has at least some merit within that less than ideal context.
I would suggest mandatory training and stress testing for anyone wishing to acquire a weapon for personal protection. Considerable resources would be required, including staffing of training centres with not only experienced firearm use professionals (police, ex-military, range officers, competitive shooters) but also psychologists and civilian oversight watchdogs. Funding might be difficult, but I believe such a program may well supplant the need for much police agency funding, so a simple transfer of funding from a nanny state police system to such a program would result in modest cost increases.
Plainly terrorists aren't going away. They're encouraged, every time there's a week of news chatter about even the most modest successes in murder and mayhem. Police agencies plainly can not deal with the initial strikes in all but rare cases - primarily those involving direct first attacks on police themselves - typically taking so long to arrive at the scenes that a handful of civilians die before they even arrive, never mind putting down the attackers. That mall attack in Africa is just a glaringly awful example of police agency (not individual police personnel) and military incompetence.
Carrying pepper spray may well be a great help in such attacks, but as such sprays are illegal to carry for self defence in many countries and regions (in Canada, for example) there's no argument to be made there which is much different from carrying a firearm. We are not permitted batons nor knives nor anything else for self defence here. I'd really appreciate a proper national debate on the subject, but in our political climate and considering the media's apparently insatiable appetite for anti-gun nonsense that seems a long way off if not impossible. Official agencies, especially police, want all the power for themselves. They are becoming more paranoid by the year regarding their own positions and safety, and that's understandable, considering that their very existence is threatened by social and political changes. Just like income tax, police were thought initially to be a temporary measure. And they ought to have been such. But power is a funny thing, people like it once they have it. And how can police enhance their power better than by eliminating non-police citizens' rights to protect themselves?