I didn't find this that believable to be honest. The fact that 12 shows up and seemingly doesn't need to prove anything, the sheriff just goes along with him was kind of at odds with the fact that this is 12 in only series 8 or 9 (and Clara wasn't with him to temper him either). Also, I didn't find the fact that this was set in the 1800s believable at all — if it had been set in the modern day that would have been a lot better wrt how the characters other than the Doctor acted, but it wasn't and they still acted the same.