Hi Lyn. I believe that the Royal Artillery in WW1 comprised the Royal Field Artillery (small, lighter guns, nearer to the front line and often pulled by horses) and the Royal Garrison Artillery ( longer range, heavy guns). The cap badge would have been the same but they had different shoulder markings (RFA or RGA). I cannot pick these up in the photograph). However, since the soldier at the front is holding a riding crop, it could suggest that they are from the Royal Field Artillery. Dave
Hope you can open thei Lyn. https://www.1914-1918.net/rfa_units_92.html
Be nice if someone could tidy the photograph for lyn.