The Hercules Model G has a 1935 Sturmey Archer Model K hub. The model K is the forerunner of the long-running AW hub, but with some slight differences. It is yet another in the long line of 3 speed Sturmey Archer internal gear hubs.
The hub script is somewhat ornate and rather nice. The imprint bears"K 5".
The gear ratio is the same as the AW: 1= -25%, 2= direct, 3 +33.33%.
There are a couple of notable differences. First, there is no "neutral" between second and third. Second, the clutch has ramped blades on it. It would be many years before the AW itself got a "no in between gear" feature.
One of the best things you can do for a K or an AW is swap the 18 tooth default cog for a 20 or 22. Remember, you may need a bigger chain for that once you're done with the swap.