:::I always thought that books wrote RP.Mk 2 with that dot to separate the prefix from the Mk letters. That makes two of us speculating on editors' reasons... Regarding the Lynx page, I was not referring to the RP.2 format (which I have always found a fine shortening), but to instances down the page where we see Mk.21A instead of Mk 21A. You will see that Wikipedia:WikiProject Aviation/Style guide/Naming (British_military_aircraft) takes the dot in Mk. as acceptable but not preferred. Likewise in this article we are discussing here, I do think your last statement missed the point somewhat. The article is about the names, the prefixes and the numbers, but not really about the formats. WP should be consistent in that the page teaching the correct names (this one) should match the page teaching the recommended format (that one). On this one page here, and on the matter of dots alone, I believe that the formats should be used so as to set a consistent example for the reader, never having it any other way but the chosen way. I believe that we even have consensus on the preferred usage between "dots" and "no dots". The only real discrepancy I see is sometimes using Mk. and sometimes Mk here, when the former is discouraged and the article is not commenting on the alternate usage of dots/no dots. 

 :::To put it shortly, I should think that, between Mk. and Mk, the article should adopt only one, regardless of which one (and I would add that both WP and I prefer the second one, but this is beside the point). Curiously enough, by now I have departed from my main points when creating this section, but I also see that we managed to pinpoint the issue where consensus and referencing can both be found.