No, I haven't seen this one before, but I think the clue is in the way the vane support tube is offset to starboard. There must have been a pair of bevel gears, like the Aries, with a small bevel gear mounted on the horizontal shaft connected to the push-pull rod via a crank, and a larger bevel gear mounted on the vertical shaft that is connected to the servo blade.
I'd guess that the vane would be similar to an Aries vane, too - a piece of thin plywood, something around 900mm high x 250mm wide.