”Brian … I can't remember writing anything about Grandfather's Clock. You'd have to remind me where it might have been.”

Derek, I refer you to:
Schofield, D. (2004) Sowing the Seeds: Cecil Sharp and Charles Marson in Somerset in 1903. Folk Music Journal 8 (6), p 497

This includes the following quote from Cecil Sharp’s Hampstead lecture in1903:

“I could easily have filled my notebook with Music Hall songs, [Minstrel] songs, or with the popular songs of fifty years ago and less, such as ‘Grandfather’s Clock’, ‘A Life on the Ocean Wave’, ‘Woodman Spare That Tree’, ‘Wait Till the Clouds Roll By’ and drivel of that sort. Gradually however we worked through that stratum and eventually struck a rich vein of Real Folk Song, of the kind we were searching for...”

It’s an excellent article, and I commend it to you and others.