In April 1950 television's aspect ratio was changed from 5x4 to 4x3. As the technology of the manufacture of cathode ray tubes improved it became possible to make tubes in a rectangular shape (albeit with rounded corners) and so more effective use could be made of the display area.
4x3 test transmission
Early test pattern
Early 4x3 Tuning Signal
Almost all of television in the early days was live and the primitive equipment (by today's standards) was prone to malfunction. Thus this title card might be shown if only the vision had failed.
When, however, there was a complete breakdown (a fairly frequent occurence), this card, usually shown on film from telecine, became a familiar part of television.
In 1952 the BBC conducted an experiment to attempt the relay of pictures from across the
This had been done in 1950 but only from Calais and with BBC equipment operating
on 405 lines.
In case of the (not unlikely) event of a breakdown in transmission, this title film was prepared.