Hospital Officers with Map of Hospital

I recently received a few of my grandfathers things and it included his ID badge from "USNTS Sampson". I had no idea what that meant but I searched the web and found this web site. What a find!

I was going through the pictures and was able to identify my grandfather, PhM3c Arthur Birnie, in one of the photos. If it's possible to add his name to the photo caption, that would be great. It's Photo #2 in the Sampson Hospital photos. My grandfather is on the far right.

He was 38 when WWII started and had already served in the Royal Army Medical Corps in the 20's. He was from Londonderry.