In the stage play Murder on the Nile, McNaught is the Captain of the Lotus (also described in stage directions as the ship's manager). After the murder of Kay Ridgeway-Mostyn on board the ship, he sends a boat to notify the police and in the mean time, appoints Canon Ambrose Pennefather to interview the passengers and investigate the case. The part only has a brief appearance in one scene with a few lines and could have been written to suit a cameo appearance.
The novel Death on the Nile on which the play is based also has a ship's manager who is unnamed but who appoints Colonel Race and Poirot to investigate the shooting.