Hi Becky,

Got it! At first hearing it sounded like 'The Water is Wide', which is definitely a closely related tune but doesn't have the flattened seventh in the first phrase. As you suggested, the clue is in the name, since RVW always like to call his hymn tunes after the village where they were collected ('Ingrave', etc). Unfortunately, according to the Roud Index, neither he nor anyone else collected any songs in Danby, North Yorkshire. Aha, but... he did collect several songs in a location described as 'Westerdale', which is a few miles from Danby. Looking through those songs, there's one called 'A Brisk Young Farmer', which is the mixolydian tune you're looking for. You can see it for yourself on The Full English - it's Roud 60 and the singer was Thomas Bowes.

I suspect that the song actually was collected in Danby, but Westerdale (which is a geographical feature as well as a village) was used as shorthand for the district he was working in.

I did a bit of work recently on RVW's hymnal. Everyone knows about 'Our Captain Calls' being used for 'He who would valiant be', but it was a surprise to me that the tune for 'O Little Town of Bethlehem' comes from an obscure (and pretty awful) folk song called 'The Ploughboy's Dream', in which a ploughboy is cruel to his team of oxen and receives visitations from both an angel and the devil to warn him on his future conduct.