Hello,
If I may add something...
This is neither ICRC-related nor Polish Red Cross vehicle. This is normal military ambulance only with Red Cross symbology according to all Hague/Geneva Conventions.
The badge I marked and described on the pic explains all. This badge was painted between December 1940 and December 1943 on the Polish military vehicles that belonged to the Scotland-based Polish 1st Corps.
Best regards
C.