I finally picked up an un-molested Enfield #2 mk 1 revolver.  Supposedly almost all of these were converted to the later #2 mk1* configuration which were DAO. I assumed thy just modified the hammer by taking out the sear slot in them when the hammers were bobbed, because it seamed like the easiest thing to do.
Turns out they used a separate sear for single action, which was semi-exposed and IMHO asking for trouble. so I took the side plates off one of each, and if I didn't know better I'd guess, as a M.E. with 35 years experience, that the 1* was designed 1st and the 1 was adapted to be a DA/SA version of it.
the 1*



the 1

My 1940 revolver was DAO but was converted post-war to SA/DA and the front sight blade was shortened to match-up with US .38 S&W fodder.

I have the correct parts/blade to put it back in DAO/.38-200 configuration but as a shooter I like it as is. I never plan to sell it so hopefully they find the bag-o-parts for it when I pass.

Yours doesn't look like it has the semi-exposed cam/sear thing that mine has. Have you ever removed the left side plate to look at the lock inside?