Okay I can tell you that Andrew Cowens wife Christian Nairn was sister to my G.G. Grandfather. Not the family I was thinking off, but I do have Andrew Cowens and family in my tree. No knowledge of Thomas Oliver Cowens, was he their son? Had a quick look at the Census records for him his wife Elizabeth and Lily but not found, can you help locate.
Also in my tree is a James Nairn married Elizabeth Maughan 1897, Woodhorn, Northumberland. This couple are also related to us.