I had a '69 (Raleigh) Triumph, and it was a little different: the gear cable went down the downtube all the way to the chain stay. The one in your photo seems to have a fulcrum on the top tube and presumably a wheel at the top of the seat tube; this means better shifting than the one I had. Whether this means yours is earlier I can only speculate, but I would speculate: yes, it is.