Since the start of the BBC, there was a need to have some sound effects available for program makers to use.
These were to start with recorded live as part of the programmes by a studio hand using all sorts of equipment to produce the effects. The item used may have nothing to do with the actual noise being created, for example a cabbage is a great vegetable for creating stabbing and saw noises!
Over time, the BBC had started to create records to record shows, it made sense that they also started to record sound effects which could either be played over a live show, or (later on) edited into it. They had the advantage that the right effect would be used, the length, noise level, and contents were known in advance. The first set of these were recorded onto 78s. They were housed into specially made covers with a thin plastic film to protect the record from scratches.
The BBC had created a catalogue number style for these to make them easily searched for and they could be replaced back in store in the right order when no longer needed. For the first set, the format was a number, a letter, then up to three numbers. If there was a set of discs with the same subject, then the number at the end would go up one for each of them. For example, 1 A 1-207 all have recordings of aircraft. You will note the record labels and run off codes used the same design as other internal records produced, the A and B sides would have different numbers (size of record, type of record and a unique number complete this matrix number.)
Many of the original set of sound effects were recorded in the 1950s, though later ones seem to have continued into 1960s. They were all recorded in mono. It is thought that very low numbers of the discs were pressed, but how many isn't known. They are now highly collectable.
The example picture presented here is one of the aircraft discs.