lucy Broadwood was a writing at a time when victorian prudery AS was the case with Sharp, MIGHT POSSIBLY have coloured her opinion.
My Opinion is that the song the Streams of lovely Nancy, is about two lovers, in my opinion, the song has strong sexual overtones.in that respect the somng has a similiar feel to. Just as the tide was flowing
The song may or may not have originated in Cornwall, the remarks about asking streamers about where the true lover is nothing more than speculation.
In my opinion both songs that i have mentioned [Streams and tide flowing] are euphemisms for sex, just the sort of thing that in 1913 Sharp and Broadwood did not want to admit to publicly and whchich Sharp and Baring Gould liked to bowdlerise so that it was suitable for children