Slim John was a 1969 BBC English Language Instruction serial made for overseas broadcast, in twenty-six episodes of fourteen minutes each, and in black and white.

Short grammar lessons are transmitted to all the robots at regular intervals via their hand-held communication devices (anticipating personal digital assistants by more than 30 years).

These short lessons are presented not only to the robots (including Slim John), but in full screen to the viewers.

The series was broadcast for years all over the world, in Turkey, Cyprus, Finland, France, Germany, Italy, Sweden, Brazil, Yugoslavia and other countries.

Hungary, Poland and Romania were the only Eastern Bloc countries to show the serial, with an enormous response, in the 1970s.