Thank you all for the quick responses and for sharing your eye for detail! Greatly appreciated.
Based on your replies, I would make the guess that the uniform in the middle picture is one taken on enlistment into the Middlesex Yeomanry. The original photograph is on a postcard and I would imagine it was taken to be sent home to family.
The other two photographs, in which he looks slightly older, would suggest that that he is wearing his scouting uniform, and has chosen to wear his military ribbon bars - perhaps a common practice amount veterans at the time?
As Alan O points out, the ribbons are poorly placed - surely no Sgt Maj would have allowed him to get away with that!
Thanks Milmed and NRM, as I said in my original post, I have never seen stars like that on military uniform and your explanation is a great starting point for further investigation!
I will continue to dig but thank you all for clearing that mystery up for me.
Ridge