The Cadfael stories by Ellis Peters are very well-researched, and her historical references are spot-on. I've read every book many times (bit of an addict) Inheritance was allowed even by an illegitimate offspring if the father acknowledged him/her, which didn't pertain in England. But there was much trading between Wales and England, particularly wool. And many Welsh speakers along the border also spoke English. English miscreants and fugitives could be safe from the Law if they fled to Wales. (The books are set in the 12th Century)

I seem to remember in the Cosher Bailey song there's a line,
"If you want a drink on Sunday
You'll just have to wait 'til Monday..." so I wonder if pubs did in fact open on the Sabbath?