What a fascinating thread from a far-off country! As a Yorkshireman I can add nothing to the brilliant research here conducted except to offer that descriptions like the 'dusky/husky black and tan' can have more than one meaning even in this context. Personally I would dismiss the Irish military connection and the Guinness connection, but the knitting and intermarriage meanings both sound very plausible and may both be intended. One doesn't have to exclude the other.