The reason for my checking out this very helpful forum has, sadly, recently left us. Keith went through the latter stages where his sister (my partner) and his children felt sure he could hear what was being said but was unable to verbally communicate. He had taken the decision previously not to be force fed with food or fluids and then it was just a matter of days before he passed away in his sleep and comfortable in a hospital bed. Happily, Keith's siblings managed to see him and he acknowledged the presence of each one. From what I understand, Keith led a varied and active life in which he invariably made his own decisions. The circumstances in which he was left by PSP, made it clear he had one more decision to make. He did this, and is now at rest.
I thank everyone on this site for the information you have provided - the majority of which I am sure has been difficult to convey - and the comfort that information has given us during that time. I sincerely hope the ongoing journeys of sufferers and carers alike are not too dark going forward. To those that have already lost loved ones to this disease or are currently navigating the final stages, I send my profound best wishes and kind thoughts. Thank you.