Hello NSWelshwoman,
The forename Lorna was (according to various online sites

) made popular by the 1869 novel Lorna Doone - you may have already read that? There were not many Lorna'a around during your Lorna Coats's lifetime. In fact there were only 7 female Lornas and 1 male Lorna

on the Scottish 1881 Census.
I've been trying to think what other name could have been abbreviated/altered to Lorna but haven't came up with anything yet.
Looby