Apparently his accent sounds Franco-Spanish 
Source: http://tf2wiki.net/wiki/Talk:Spy#Country_of_Origin

Source: http://tf2wiki.net/wiki/Talk:Spy#Country_of_Origin
the spy was always british in my eyes. like very upper class country / down south.
Hes Australian!
"God save the Queen" sounds british to me, i tihnk i have heard him say "G'Day mate" though so maybe he is a mix. i always thought being the Sniper in a game was a British trait though?
theres going to be a feature length tf2 movie btwSo we will find out everything sooner or later xD
from what ive heared yup.