I've checked around in a few books but can't find the source of this notion I have: that the "husky black and tans" are a regiment of militia and "home rule be protected" refers to some pre-confederation British colonial policy of limited local self-government. The narrator resents the possibility that his local regiment will be disbanded as potential insurrectionaries; that London will meddle in Cape Breton affairs; and that Newfies will undercut the locals to grab what few jobs are left. Times are that hard some Capers stoop so low as to join the constabulary. Or something like that. I might have read this in a Helen Creighton book I borrowed from the library.