For the benefit of anyone interested, see this photo
(from this splendid website
http://www.godfreydykes.info/THE%20ROYAL%20NAVY%20WARRANT%20OFFICER%20PART%20ONE.htm)
The chap on the left is a Warrant Officer, a
Carpenter by title. Of note he has neither buttons nor rings at his cuff, no patch badge on his right arm, and eight buttons on his jacket. That's a very specific combination that the website's knowledgable author doesn't understand, yet the contemporary text identifies him as Carpenter. It may be this particular style lasted only a year or two, uniforms were in a state of change.
Note two of these W/Os have the extra buttons at the lapel, albeit "unbuttoned" i.e. nearly hidden beneath the lapel.
The cuffs in the original query photo worried me, but I have found a few photos now of Warrant Officers and Chief Petty Officers of the period where the camera has picked up vertical pleats or stitching at the cuff (also implying the cuff is either a separate piece sewn onto the sleeve, or a deep turn-up - often disguised by rank rings).
I begin to think it's just a freak of the photography highlighting an unimportant bit of tailoring. Perhaps even residual tailor's chalk? on a brand new uniform.
The cap badge is still a bit dubious, but I think we are only seeing the bottom half with the top half in shadow. The apparent "crown" is the bottom of the anchor in it's bowl of foliage.