Proto Go-Pro

I wonder how Jackie Stewart controlled the shutter on this early attempt at onboard driver-controlled photography at Monaco in 1966. Do you think that cable stretched down to the steering wheel? More importantly, where do you think his photos from the “35mm Helmet” are?
Monaco in 1966 would have lined up nicely with the production of John Frankenheimer’s Grand Prix. I’m speculating here, but perhaps this is how some of the stills for the posters, premier program, and other ephemera were captured.