is this a ww11 tunic ??
From these pics, yes a WWII 40 pattern austerity, though pics of the inside would help. Impossible to comment on the insignia from these pics.
Whatever its just an opinion.
As Jerry said would love to see more and the interior, insignia closeups as well.
Initial thoughts are yes it's a 1942-1946 produced blouse (not tunic). Shoulder titles look too low on the sleeve (and are of a post-war pattern I think?).
Backing colour of the pips is wrong for SAS; early war plain khaki was worn and from 1943 onwards it was Cambridge blue. I would like to see close ups of the insignia; the shoulder titles do not appear to be genuine.