DeHaviland Airscrew Control

I have GA drawings of both DH and Rotol airscrew pitch controls for their respective CSU’s. I can not, however, find a good clear photo or drawing of the DH 20deg PCP control. The original, mounted on the left hand side above the elevator trim and predating the lever fitted to the throttle body.

Does anybody have anything they could share with me?

thanks

Tony