Wounded servicemen wore Hospital Blues while recovering.
The jacket was blue with a white lining which showed at the lapels.
I have seen examples with no lining. Most have white buttons
The tie when worn was red. Hospital blues are more commonly seen in group photographs than individual portraits.
Troops often wear their caps in these pictures which may be a way to identify a man's regiment from the cap badge.
Usually there were no badges of rank on hospital blues and for some reason the jacket had no pockets; however I have seen photographs with both these.