@Wiltingasparagusfern
Sally Walker has, over the last seven years, both in her books and in interviews, said that in 2013, just as they lost their home, that her husband Tim was diagnosed as potentially having CBD, a terminal disease. She has said they couldn't confirm the diagnosis because that could only be done post mortem. She has spoken freely about consultants in 2013 saying he would be lucky to have another two years of life.
However, he was actually diagnosed with potential CBS, in June 2015, two years after the walk detailed in TSP. CBS is a syndrome that shows symptoms, and they were, as stated in the letter by the consultant, very mild.
In her books she states how going on long walks of over 600 miles across challenging terrain reduced the symptoms of his terminal disease, and in her last book (Landlines) said that brain scans of before and after their most recent walk show that the disease had regressed.
CBD doesn't regress, it just gets worse, and is usually fatal within about 8 years.
CBS on the other hand, can be fairly mild, and was in Tim's case, as evidenced by the letter Sally Walker herself produced.
That's the issue.