Information on individuals.

[DEEDEE]

I have just been given a photo of my Great great Grandfather there is a number on the back could this be his Regimental number? It is 2245 ,His name was Patrick Glynn.
Is there any information' on this number please ,It would be fantastic if I have at last found him and what he did when he was at Norton Barracks, I know he may have been previously at Pembroke Dock. Thankyou DB.