Graham, Have you located info on your Edward Porterfield? I have lots of info on Porterfields including the Frank B. Porterfield book. My grandfather, Ernest C. Porterfield, passed away this week. He and my grandfather did extensive research on the family ancestry. They visited the Porterfield castle, Duchal. We do not have a tartan but are associated with MacNaughton clan. Salado, Tx has a Scottish museum with many of the tartans and info. There is a relative in Ireland named Nancy. .I'll find out last name. She is still living and had visited my grandparents here in Texas. Let me know more of what you're looking for. I would love to help.