Hi Jamjar,
Many thanks for this. I have just sent them an email to see if they can help. From what I have gleaned in the 1841 census, there were a few other households in the area, inluding one referred to as Tinwald Mill Dwelling House.
I note your ggg-grandmother was Grace Morrison-Jardine. My ggg-grandmother was called Helen Jardine before marriage and she lived at this mill at least until 1850.
Maggie