Marje wrote;

"Bubblyrat, the tune that's used for To Be A Pilgrim is indeed a folk melody that was collected in Sussex, and had a previous and parallel life as The Blacksmith"

It was Vaughan Williams who adapted the tune for "A Blacksmith Courted Me". He took the original modal melody and rewrote it in the major key for "To Be a Pilgrim". The tune is called "Monksgate" in the hymn books, named after the village in Sussex where Vaughan Williams Collected the song.

I haven't heard the Shirley Collins version, but I have a recording of Jo Freya singing "Blacksmith" to the Monks Gate Melody. It's a gorgeous melody. On the recording she is accompanied by a Viol Consort which works wonderfully well. At least I think so.

There is a different tune to "Blacksmith" which was collected in Herefordshire. Steelye Span have recorded that version - among others.