Grain Mk1 sewing machine, green
Grain Mk1 sewing machine, green(i)
The very first Mk1's were supposed to have been released in black in 1947, and were then changed to a green finish, with a red finish then used for the "premium" versions with more accessories (carry-case, leg supports, etc.).
This is a green example ... while this means that it's no earlier than 1947, we don't currently know the date at which the switch from black to green happened.