He is indeed in the Leinster Regiment, whose depot was at Birr. The metal badge on his right upper arm shows him to be a regimental bandsman (it is a lyre with crown over and shows him to be competent), which might help with your research.
Frogsmile - Thank you for that - only seeing your post now. Yes - I have been told that the brothers played in a band... Must have been the army band. Lovely to have some evidence of this. Regards, Michelle
I was glad to help Michelle. The Leinsters were a good regiment and unusual in that they were originally raised from Canadian volunteers at the time of the Crimean War. As a result their secondary title was the Royal Canadians. The piece of felt visible behind his gilding metal band badge was scarlet in recognition of the regiment's Royal status.