Jack Holbine was a filmmaker during a time when humans used time travel to make films. He specialised in historical films, travelling to historical times to record events. When he was on an assignment, he used force fields, holocameras and a hologramatic projector.
When a film was being made of Edward Grainger's life, Jack was assigned to film Edward's father's assignment during the Gallipoli campaign. In an attempt to make the film more interesting, he accidentally changed Lawrence's future and tried to help the Fourth Doctor restore the timeline. When they failed, Jack spent the rest of his life as an Australian soldier. (PROSE: Direct Action)