So, 50 years on, does anyone use them?
A PARTIAL UPDATING..
In the past Century Jeremy.. I came across ‘Betalights’ in a delightfully shaped Household Telephone called a ‘Trim-phone’..
this was around 1972.. Executive wives had them installed and waxed eloquently of their Beauty..
until the Chagrin of reality BIT them.. During all telephone calls.. Every time they had covered the mouthpiece..
to ‘whisper a home-truth’ to a companion.. every Intonation had been Amplified and transmitted asper Normal use!
Satan himself must have designed the phone.. as the audio input was actually a small hole near the Earpiece.. some 4inches away from the Mouth-piece of the phone..
Several decades later in 2001.. 2 ‘betalights’ were installed in every BT wall mounted
‘Call Line Indicator’.. I doubt very much that the word ‘Radioactivity’ ever featured in the awareness of many fitting/using/disposing of them.. so local waste in the Grey Bin I guess?. Enjoy seeing your Innate Curiosity Jeremy.