*::::Just to be clear, I'm suggesting/supporting "John Arbuthnot Fisher" because, according to the most general Naming convention, the title should be "John Fisher" (outside of WP:UCN, for which I haven't seen any real case being made). "John Fisher" needs to be disambiguated though, and I don't think that this "John Fisher" meets the requirements to fulfill WP:PRIMARYTOPIC for that name. So, the first means of disambiguating is by adding a middle initial or name. Since he (apparently) actually used his middle name, that naturally leads to "John Arbuthnot Fisher". All of that being said, I should state that I don't have a real issue with using peerage as a disambiguator, which is what the other option is doing. It's simply not as standard a tactic, in a Wikipedia-wide sense, is all.—