I wish to make a commercial PC video game based on the British commando units from 1940s that have been disbanded in 1946.
The unit is "No.3 commando".
Is the use of names like no.3 and commando permitted in the name and other text in a video game? Same goes for insignia.
In case it requires special permission, which institution should I contact to seek the said permission, since I'm not a UK citizen?
I have heard about crown copyright that expires after 50 years but haven't been able to find enough information pertaining to commercial uses.
Just for reference, an existing game that uses such names and markings is "commandos behind enemy lines."