Good grief, I am not "threatening" people with ill-health. What do you think I am, some sort of Dr Evil about to unleash biological warfare?(strokes white cat) However I genuinely think that this issue, however much of an irritant, is trivial compared to the many more important issues of patient safety that the NHS has still not fully addressed.
Before I became a doctor, I was the primary carer of a dying relative, so I have been on the other side of the fence in some very distressing situations and got called god knows what and treated in all sorts of undignified and rude ways. However, at the end of the day, most of the time, my relative got the care he needed and that was the most important thing to me.
Unlike most posters of this thread, I would guess, I have also lived in the US amongst other countries and that has made me a passionate defender of the NHS. I say again that, if the worst that happens to you as a parent is that you are addressed in a way you do not like then that is a fantastic tribute to the NHS and not an inditement of it. By all means pick people up on it - I agree it's rude. But do get some perspective.
I'm going to leave it there because, on reflection, I'm proud to work for a health service where being called "Mum" is apparently a major issue for many people. If that is the worse that parents experience, then we are doing pretty well.