I have submitted this request to theSession (www.thesession.org). But I thought perhaps someone here may be able to help.

The introduction to the Corries' version of 'Collier Laddie' sounds like a slow reel. Does anyone recognise it as a traditional tune, or is it likely to be a Roy Williamson composition?
My transcription of the first part is this: (I am new to ABC and transcription, [and everything else] but it is fairly close!))
X:1
T:Collier Laddie
R:reel
M:4/4
L:1/8
K:D
|:A2|ddAG FABA|dded cAAA|BAGF GABc|dded cAAc|
ddAG FABA|dded cAAA|BAGF GABc|ddec d2:|
I am still struggling with the B part