Jim,
The people being recorded in Germany in WWI were mainly young men sent out to be cannon fodder.

Joseph Taylor was certainly not nervous. He was a confident, well-respected member of the community, a churchwarden if I remember rightly, an estate manager? He certainly wouldn't have been fazed by Grainger. Apart from that Grainger would have heard him sing the songs before recording them as they were part of a competition, and would have acted accordingly.