I could be wrong, but this machine looks to me like it could be older than a 1960 model, judging by the paint and the forest green keys and a light green wrinkle-finish shell.  I have a 1958 Remington Letter-Riter (essentially a Quiet-Riter without a tabulator and has only 42 keys--no +,=,1, or !.  Gotta be creative just like in the forties on back, at least on the American varieties) that has keys more of a jade green color, and the shell is painted a semi-gloss grey.  It could be possible, though, they may have used the two colors side by side.  I remember looking at a '55 Underwood 150 that was sandalwood with cream-colored typing keys and turquoise surround (shift, backspace, margin release, etc.) keys.  I once swore that was something they started doing in '56.  Anyway, just sayin'--puttin' it out there.