BBC Transcription Services
The BBC Transcription Services started life in the mid-1930s as The London Transcription Service to license BBC Radio programmes to overseas broadcasters who were authorised to broadcast the programmes for a set period, usually 2 or 3 years. The programmes sold to overseas broadcasters in this way covered every part of the BBC's output, including all types of music, drama, religious and children's programmes and comedy. It is now called BBC Radio International.
Whilst the BBC destroyed most broadcast recordings it produced for its various outlets, BBC Transcription Services often retained their copy and many of the surviving radio programmes from the 1940s onwards owe their survival to the fact that a Transcription Services issued the material.
The original releases were in the form of 12-inch 78rpm discs. Each of these discs contained no more than 3 or 4 minutes per side and so a radio operator would have needed to cue the start of many discs as the previous one finished for a half hour programme. Consecutive parts of a programme were on different discs to enable the radio operator to cue the start of the next part of the programme from a different disc from the one being played.
By around 1947, the 78rpm discs were replaced with 16-inch transcription discs running at 33⅓rpm. These coarse groove discs each contained approximately 10 minutes per side, so the requirement to cross fade throughout an episode was still required.
Typically BBC Transcription Services pressed 100 copies of each disc only with instructions to the overseas radio network to destroy the disc at the end of the licence period.