Hi Lesley,
Genuki has an online gazeteer for Roxburghshire. I couldn't find Blackcleughmouth on it, but I did find Blackcleughrig and Blackcleugh - both in Teviothead parish and Black Cleugh in Castleton parish. There is also a Colliforthill in Cavers parish. I am afraid that there is nothing for a Shuttlehall - Slatehill in Teviothead was the closest I found. Cavers and Teviothead parishes lie not too far from Hawick parish, to be considered in the same area, and Castleton is not much further away.
Cheers,
Clare