Christian name left blank in his daughter's marriage entry in 1st Kilrea Presbyterian Church records - damn! However, there is a James Cooke from Dullaghy and the son, James' marriage is recorded on a civil registration certificate in Boveedy Seceder church. The marriage certificate gives his address as "Dulachy" and his father's name also as James. There are very few McCookes in Dullaghy and James son of James called his daughter, Nancy.
Also, there is a James McCook's marriage to Mary Ann McIlhouse recorded in General Registry Office Marriages index, Belfast taken from 1st Garvagh Presbyterian Church, book 01 page 07. However, on checking the Bann Valley site's 1st Garvagh records, there were three James McCookes marrying at about this time!
The 1831 census for Dullaghy shows only one McCook in Dullaghy and his name was James, he lived in House 13 in a household of 3 males and 5 females, all Presbyterian.
The TAB shows a James a James McCook holding 19/3/7 arps in Dullaghy.
THis extensive tree is at A.com but, while it might give more info on some minor characters, I do not thnk it has anything new on the people closest to me (in fact, it has an error on the Gordon side:
http://person.ancestry.com/tree/27562964/person/240040318482/facts