During the 1950s and 60s a freelance photographer called John Cura was commissioned by the BBC to take photos from a TV screen of various series. These covered most scenes in a story and amounted to around 70 stills per episode. They were used as a visual and continuity reference to the episodes by the Doctor Who Production Office and copies were often retained by directors and occasionally cast members as a record of their work.
The standard format that the telesnaps were printed in was as 'contact strips'. The individual pictures are very small, approximately an inch across, but very clear. Occasionally copies of individual telesnaps were ordered, these were enlarged to about 2 inches wide.
It is thought that almost all early episodes of Doctor Who were covered by telesnaps, however the BBC Written Archives only holds copies from The Gunfighters through to The Dominators. Only one episode is missing from this run: Enemy of the World episode 4, it is unknown why this episode is not covered. Other telesnaps have emerged from private hands, most notably from the serial The Crusade, which were rescued when they were about to be thrown out of the Production Office in the late 1970s. Several directors were also known to have kept telesnaps of some of their work.