Regarding Rangers demotion to the Scottish Third Division today, Dunfermline chairman John Yorkston said, “The vote was 25 to five so I think that was fairly unanimous." You can't be 'fairly' unanimous any more than you can be 'somewhat' of a virgin, can you?
29-1 might, at a linguistic stretch, be fairly unanimous, if "fairly" can be thought of as meaning "almost" (which it probably does in this case). But 25-5?
Very has been used as an intensifier with words such as first, last, next, best etc since the 1500s, so I don't consider that a mistake as I do with fairly unanimous. Certainly, adding very does not alter the actual meaning of the overall phrase, but the additional emphasis it supplies is acceptable in my view.