Reading about the 1954 Timex Magnetic Disc Recorder, which Bill Burns suspects was never put into production I can say with certainty that an earlier magnetic disc recorder, which is similar to the description of the Timex except it does not play 45's, was put into production as early as 1950.
I recently acquired a Recordon, which was made by Thermionic Products of London. Capacitors inside are dated April 1950 and seem original, so I assume that the machine was built circa 1950. It was made under licence from the Brush Development Company of the USA, and the circuit is a fairly simple three valve (tube) affair not disimilar from simple tape recorders. There is no power amplifier, the Recordon is clearly intended as an office dictation device with remote control and headphone level playback both available via the microphone with a foot switch as an extra option.
I received my Recordon without a mains cable, but a quick inspection of the circuit allowed me to construct a cable. The machine fired up immediately and after giving it a few minutes for the (original Cossor) valves to warm up I was able to replay a recording made on the machine almost 50 years ago. The only disc I have, which was attached to the machine when I purchased it, contains a recording of a doctor dictating medical certificates to his secretary. One is dated 27th January 195? (a dropout muffles the final number) but other information on the disc (he mentions a flu epidemic) leads me to conclude that it is the early 50's.
It seems somewhat remarkable, but the magnetic recording has survived almost 50 years in such good condition and with so few dropouts that the contents can be easily heard and understood today. Apart from that last digit in the date every word can be discerned. The disc runs for about five minutes, and the fidelity is not very good - adequate for dictation and other voice recording but not suitable for music. The recording runs from the centre out towards the edge, with the quality getting better the closer to the edge the pickup gets.
The discs have 'fold here' dotted lines on them suggesting they can be mailed (as with the Timex discs) or stored in the machine's lid.
I have not tried the recording function because I do not wish to damage the information already on the disc. I have enclosed a picture of the machine itself and one of the instructions. I apologise for the length of the file, my work computer's software can only handle bitmaps.
All in all it is a fascinating machine, but must have had a short production life once dictabelts and dictaphones hit their stride.