It was the 1st of May 1916 and my briefing was to watch carefully what the pilot does and learn from his actions.
I have no idea what that thing in front of his face is or what purpose the handle bit plays .....
I believe it could the engines decompression handle.
On early engines and before starting, the cylinders were primed with fuel by hand.
To allow the engine pistons to be moved and fuel to be added into the cylinders, the engine was turned (by rotating the propeller), moving each cylinder in turn.
The decompression handle was fitted on the rear of the engines cam shaft
When moved it altered the position of the cams on the camshaft, easing the valves and releasing the pressure inside the cylinders.
This allowed the propeller to be rotated by hand to move the engines pistons.
After fuel priming, the handle was moved back to the flight position.
Later inline engine had priming pumps fitted in the cockpit so the pilot could prime the engine cylinders.