It's interesting how quickly technology changes, particularly something as common as a throttle.
My 27 has a throttle lever, as with most previous models (Air and Mixture levers).
I think most of the 30's models, well 1" bar models anyway, had the longer travel internal type throttle, with a different type of rubber grip. I know at least until 1937 does.
Red Hunters may have had a Bowden quick action twist grip from the early 30's - but there's no mention in the catalogues (that I can see at least).
So, it's possible (I could be very wrong) that your W/NG was the first Ariel model with a clamp on throttle?
'51,'56 Squares, '48 VH, '27 Model C, R67/2, Mk IV Le Mans, '06 Super Duke and Ariel projects.