Interesting photograph from battiscomme.

This Sgt appears in an artillery Battery photo - a Sgt of some kind - shoulder titles (it looks a bit like ASC but not convinced it is). Some kind of specialist badge over the Sgt chevrons and below crown - any suggestions welcome what this might be.. thanks. AOC Artificer - might that be possible.? Might this suggest RGA or did everyone have Artificer Sgts?

Source: Artificer? Badging in artillery unit? ideas?

I had come across the Artificers joining units but was never sure of the cap badge. This looks to be the start of the Battery fitter sections providing first line support.