Here for the record is the Breton tune as I first learned it - I came across this booklet before ever hearing the Scottish ballad. There are quite a few rhythmic differences from the way most people sing it in Scotland these days, and bugger the folk process, I like the original better.

  X:1
  T:An Alarh
  S:Kendal'ch: "Kanomp Uhel", Cooperative Breizh, La Baule, 1977
  M:2/4
  L:1/8
  Q:1/4=80
  K:AMin
    E|       A  B      c  z | A2 G      G   |[M:2/8] A
  w:Eun      a- larc'h eun,   a- larc'h tre-         mor
    E|[M:2/4]A  B      c  z | A2 G      G   |[M:2/8] A
  w:Eun      a- larc'h eun,   a- larc'h tre-         mor
    c |[M:2/4]c    d    e>    e   |d>   c  (c2 | B4)||
  w:War       lein tour moal  kas- tell Ar- vor_! 
  P:Chorus
     A   B    c     B/   A/ | A    G/   G/  A z |HE2 z2|
  w:Din! din! daon! d'an em-  gann d'an em- gann, o!
    A    B    c     B/   A/ | A    G   HA2     |]
  w:Din! din- daon! d'an em-  gann ez   an!

I never met Blythman, but I once sang "The Twa Corbies" that way with one of his close friends listening: she thought he would have liked what I did with it. (I was using a Black Sea fiddle for a drony accompaniment, no attempt to boogie it up as most singer-guitarists do).