Private Selbourne is a soldier serving in the Royal Army.
Apparantly, Selbourne doesn't live close to Gurune Gate, as he mentions having a daughter that he doesn't see very often. He did mention that when his daughter came to visit Gurune Gate shortly before the events of the game, she was jealous of him working at such an impressive place though he mentions she didn't seem aware that guarding the wall is a tough job during cold winter nights or hot summer days. Still, he enjoys his job and is happy with it.
In Chapter 4, he also mentions having spotted a girl on the fortress wall a little while back, but when he took a second look, she was gone.