Hi Rory,
I have a photocopy of Tannahill's hand written letter to R. A. Smith of the full five verses of The Braes o' Balquhither.
The only difference is, in the original manuscript, Tannahill has written the last two lines of verse 4 "Till the dear sheeling ring, Wi' the light, lilting iorum".
He has underlined 'iorum', which is a rowing song.

I'm sorry I can't enter into any correspondence but you can email me at jawwmac@aol.com