Hi Heather, don't know if this will be helpful, but I do know that there were, and still are, mclatchie families living in New a Cumnock. If you type into Google - Mclatchie New Cumnock, you will see quite a few references that may be worth browsing through. Also 2 very good websites,
A. New Cumnock Now and Then. Website of Stephen Kennedy
B. History of the parish of New Cumnock. Website of Robert Guthrie
(Type those into google, I am tapping this on my ipad, and haven't quite figured out the copy and paste thingie yet.)
Both these sites have lots if good info and also guest book/forums, Robert Guthries site forum has several mclatchie entries, and even someone who has his own Mclatchie website, shows the link, and who has gathered a lot of old McLatchie info. Both sites have plenty of old photos too.
Hope this is helpful. I had a lot of assistance from those two forums a number of years ago when I began my own research, which ultimately led to me heading off to New Cumnock to meet my families there. My own grandparents were from New Cumnock.
I wish you well, and if you do strike gold let me know because I have a number of New Cumnock books written about this special mining district, and in particular the families who lived and worked there.
I also have a couple of excellent photo CDs, sure that there are some mclatchies in there, I'll check it out anyway, and I can tell you what there is, and advise you where you can order the CD. These were done by a friend of mine who grew up in new Cumnock, and he has made several excellent historical CDs.
If you manage to make a connection, please don't hesitate to PM me with your email address, and I can see what I can dig up for you. (Yes, I know, please pardon the pun, but if you saw my boxes of historical stuff, you would know that I really will need a shovel to dig through it!)
Best of luck and happy hunting.
Jeanne