Usage and Grammar

Q. I’m having an argument with my English teachers over what I think is a grammatical mistake in Doyle’s Sherlock Holmes story A Study in Scarlet. The sentence in question is: “The Daily News observed that there was no doubt as to the crime being a political one.” Since I’m fairly certain “being a political one” is a gerund and not a participial phrase, I think that crime should be changed to crime’s, but multiple English teachers have told me I am incorrect (yet the arguments they presented do not make sense to me whatsoever). Is the sentence correct as is, or did Doyle make a grammatical mistake?

A. We are in awe of your perseverance, not merely in investigating this controversial construction, but in doubting the advice of multiple English teachers. But when such a noun (crime) follows a preposition (as to), the possessive with a gerund is optional. Please see CMOS 17, 5.114 (on “fused participles”) as well as the last part of 7.28, for examples.