Thanks Wojtek. Now I just need to find out if I can trace s/n MM4462 to a production date.
EDIT 1: One of the references provided by Geo indicates that it was produced in December 1939, so grey it is.
EDIT 2: However, a restored CR42 in Italy displays s/n MM 5643. This one would have been built in 1940 but it displays silver undersides!! So confusing.