Prout self steering from prout factory?

[classicone]

I recently came across a historical photo from Ian Hawks (Prout manager) of a swift being sailed down Small Gains Creek. In the background is a catamaran with a self steering kit with a Prout logo on the steering sail. Anyone ever see one of these units in person? https://www.canveyisland.org/people-2/6 ... t-builders
It is on the cat on the right side of the photo with another that looks similar in the far left.