Hi Joker,
On IGI, there is an extracted record of marriage between John Horn an Marion Blackie on 15 March, 1850 Tranent, East Lothian, Scotland.
On the 1871 census there is a John Horn, born 1854, his mother and head of household is Marion,
48 who was born in Tranent.
Woah, I have just noticed I have a Mary Maxwell Greig in my tree, born 29th Nov 1856 in Cockenzie, daughter of Robert Greig and Jane Horn. She is the youngest sister of my GGGrandmother, Martha Greig, there were 16 in the Greig family, and Mary was the baby. I have quite a few of the family you are talking about.
Tom
PS very confusing, horn with an e or without an e