Hello,
I realise this is a long shot, but I just discovered your post about the Hume family of Greenlaw. I've been trying to trace the family through Walter Hume, the brother of George. Please could you give me some more information about George? How did you manage to trace him from London to Greenlaw?
I'm also interested to know more about his career in brewing.
Hope that you see this. I realise that your post is almost 9 years old! 
Hi PMcK, Between Colin and yourself you've recreated what I eventually found. Linking George to Thomas H and Janet Coltherd was a hunch in the first instance. I'd based it on the account in George Hume's
Thirty five years in Russia . I them looked at the death records and went trawling through Scotland's People. Ultimately I found the siblings that Colin located. I never found any link to the Humes of Marchmont or anything like that. The subsequent research here really does shore up what was mostly a theory. You asked about the brewey side of things- I looked a couple of times but hit a brickwall. I'm rather galvanised by the discussion you've created here. I haven't looked at some of this stuff for ages - I can't even find where I'd located a free online version of 35 Years in Russia. I'll post more once I've done a bit more of a recap. Thanks for bringing it up after all these years!