Great to hear from you. Loudon was indeed a South Derry name. May Scott and Cam Derby were the experts on the Derbys but are both deceased.I have only done a limited research on the name as my other close relations keep me fully occupied. My great grandmother was a Sarah Derby 1844-1915 of Derrygarve, Castledawson. Mrs Scott gave me a little of her Derby research but I cannot locate it at present. I'd be delighted if you could give me your email address and will be in contact when I find out more. By the way my father was James Stephen Alexander Derby Garvin 1916-1970.