for Bdr Arthur G Figg, the number L-25986 indicates he was in one of the locally recruited artillery Brigades - which narrows it down to units in range 148th Brigade through to 190th Brigade [ a link here lists them.. numbered with Roman numerals
http://www.warpath.orbat.com/artillery/rfa_btys_wru.htm] . with Divisions in the 30th-40th range. I think the Welsh division is unlikely as most men had a special welsh W- prefix.
I have men of 149th (County Palatine) Brigade arriving that day in France with 30th Division but there may be other possibilities..his number is a bit high for that. 168th (Huddersfield/Rotherham?) Brigade is also a possibility .. lots of men in that number range and i think it arrived around 28/11/1915. There are no such units in the west country so it depends on where he might have been working and joined up.. in 1915. Its difficult with the artillery ..