The actors that were gathered for the film included recognised stage and screen talents such as Eric Portman, Hugh Williams and Godfrey Tearle as well as newcomers such as Peter Ustinov making his film debut. Although mainly centred on male roles, Powell encouraged Pressburger to create a number of significant female characters. The result were strong, credible roles for both Pamela Brown and Googie Withers as female Dutch Resistance leaders. The main leads, Hugh Burden, Eric Portman, Hugh Williams, Emrys Jones, Bernard Miles, and Godfrey Tearle, formed the crew of "B for Bertie" and introduced themselves and their characters' positions on board the bomber in a progressive sequence that was filmed, like most of the aircraft interiors, in a Vickers Wellington "shell" supplied by the RAF, with working features such as lighting and electrically powered turrets.