And here's the set that Vaughan Williams and Ella Leather collected from Esther Smith, May Bradley's mother, 50 or so years earlier:

%abc-version 2.0
X: 3
T: On Christmas Day
M: 5/4
L: 1/4
C: Traditional, collected from Esther Smith by Ralph Vaughan Williams
Z: Ralph Vaughan Williams
S: Collected by collected from Esther Smith, Dilwyn, Herefordshire, 1912 by Ralph Vaughan Williams
I:linebreak $
K: Gaeo
D| (G A) B c A| (G/A/) (G/F/) D2 d|d c (A G) F| G (A/c/) B2 c|$
w: On Christ--mas day it hap--pened_ so, Down in those mead--ows forth to_ plough. As
[M:6/4] (d> e) (d/c/) (B c) (d/e/)|d B A3 (c/>B/)|[M:5/4] (G/F/) D (F G) A/ c/|c B HG2|]
w: we_ were_ plough--ing_ on so fast Up_ comes_ sweet Je--sus his-self at last.


This tune is pure Aeolian. May Bradley's is except for the single E natural. I thought that might have been a mistake when she (May Bradley) sang it, but she uses it in several verses.