Just a last thought on this, which may put things in perspective (and I do believe that there are many areas of H&S where perspective has been lost). One of the factors in risk management is the Value of Prevented Fatality (VPF), put crudely, what is the limit you are prepared to spend to save a life.
Now, if a hi vis vest costs £5 and the RAF buys 50 000 pa, it has cost £250 000. If , for simplicity sake, the VPF is £1m and you show that by spending £250 000 you save even one life every 4 years, you have 'broken even' so to speak. So why shouldn't it be done? The family of airman x, killed by a crew bus when he wasn't wearing one will be asking the same "Why?" questions that Tappers Dad, Nigegilb etc etc are asking (and they have my sympathy and support), and why not? If it is reasonably practical, then do it.
sw