I think the fact that he was 'well-read' is important. The information that his grandfather played clarinet in the church band presumably came from Walter. How much of what Walter knew about a church band came from the family and how much did he get the same way as a lot of us - via Thomas Hardy.

His observation about the meleodeon bellows pull "And you go right back to the beginning of the nineteenth and eighteenth [century], they finish this way, pulled out, look." begs the question - how did he know those tunes went back that far. What else had he read?