Wikipedia
Tele-snaps (often known as Telesnaps) were off-screen photographs of British television broadcasts, taken and sold commercially by John Cura (born Alberto Giovanni Cura in Clapham, South London, England; 9 April 1902 – 21 April 1969). From 1947 until 1968, Cura ran a business selling the 250,000-plus tele-snaps he took. The photographs were snapped in half of a normal frame of 35mm film, at an exposure of 1/25th of a second. Generally around 70–80 tele-snaps were taken of each programme. They were mostly purchased by actors and directors to use as records and examples of their work before the advent of videocassette recorders.
For many early programmes tele-snaps are the only surviving record of their appearance. From the 1990s onwards, tele-snaps have often been used by groups of fans to recreate lost Doctor Who episodes, creating "reconstructions" by marrying the images to fan-recorded off-air soundtracks of the episodes.