Cecil Sharp collected at least 3 carols from Mrs. Reservoir Butler, aged 68 of Armscote, Warwickshire on June 17th, 1913 according to "Carols" by CJ Sharp, F Kidson, LE Broadwood, RV Williams (1914) Journal of the Folk-Song Society, 5(18), 1–30., available at https://www.jstor.org/stable/4434000. You can read that article via sci-hub (just append "https://sci-hub.mksa.top/" before the DOI which is "10.2307/4434000") if you want to read the whole thing. There are six uses of "Butler" in the text which lead to versions of "The Holy Well", "God made a Trance", and "Christmas now is drawing near at hand", in that order... She is described as "a gipsy".

I have not found any further information, although a couple of later sources repeat the same, in one case getting her age wrong (67 instead of 68)...