VH Grumpy, I dont really understand where you are coming from, forgive if I am being stupid but I dont see what you are trying to gleen by asking the questions you are. You are an Aussie civil servant, with all due respect, that doesnt give you the right to get info on highly sensitive policies regarding the security of UK airspace. Like you have claimed there is a plethora of info in the popular media, which I guess this website is, but you cant expect anyone on an anonymous forum to be discussing whether we will/wont "shoot down an airliner". Lots of people have signed the Official Secrets Act with varying degrees of access to sensitive info, doesnt mean to say that they can have access to anything which is "secret"
As has been said it is need to know, and those that need to, do. It is bound to be an emotive subject, and no one is denying your right to ask the question but you wont/shouldnt find any serious answers in this forum. Whenever this topic is raised it descends into a fairly heated argument which never achieves anything other than distort the reality that there is a serious job to be done with incorrect facts.