 Complete the following phrase:  Wright was responsible for the aerial shots of the train from a hired aircraft, while Watt filmed the interior and location shots. The men in the sorting coach were real Post Office workers, but filmed in a reconstructed set built at the GPOs studio in Blackheath. They were instructed to sway from side to side to recreate the motion of the moving train which was accomplished by following the movement of a suspended piece of string. Early attempts to simulate motion was done by shaking the set, but Watt wrote: It just rattled like a sideboard in a junction town. Attempts to film while shaking the camera also failed as it merely produced a wobbly shot. Among Audens first tasks as assistant director was taking charge of the second camera unit as they shot mail bags being transported at Londons 