I have found this thread quite interesting and informative and particularly so as a person who has gained advanced academic qualifications and is entitled to be addressed as "Doctor". I have not used the term for a very long time and most people either address me by my Christian name or as Mister if they don't know otherwise. Just like military ranks and titles in the services have a purpose so do civilian ones like manager, supervisor, director, etc.. However when a civilian stands down, gets fired or retires the rank or title ends at that point. So why not the military ones?
Just a couple of maybe useful points. I admit to using the title Doctor when I have anything to do with the Health Service or medical things in general. I have two reason and the first is using the title Doctor more or less ensures that I will be treated as a person of some intelligence rather than that of the Village Idiot. Secondly my age - now in my ninth decade sometimes I feel that being over 80 can mean being treated as someone with a mental age of two who should be parked in the old folks home.
Finally regarding the Health Service. If you are an ex-service person do make sure that you GP and the local health practice have your records marked accordingly. The reason is that we are supposed to given a "priority service". I do not know whether or not this works across the UK but I have seen it work here in West Wales regarding hearing problems, hip and knee problems.