Ever bought a roll of bin liners from Sainsbury's?
Some of them were quite good. Charles Saffrey built a number of radio controlled model hot air balloons which, for some reason, presumably size, had to be registered. Bernard Martin of Air Britain bought a couple, G-BERN and G-BFBM if memory serves, then several years later it became a craze and spotters built and registered them in huge numbers - the G-BI** sequence was stuffed with them. I saw a couple being surreptitiously shown to other out of a car boot during the Icicle Balloon Meet at Marsh Benham in 1981. The CAA then allocated the G-FY** sequence. I think I decided not to collect the registrations as I didn't consider them real aircraft worthy of my attention! A Mr Wakelin agreed and registered G-ZZZZ as a Pointmaker Mk1 balloon which I believe was never built!
Pic here of a Rango:
https://abpic.co.uk/pictures/search?...&source=g-info
Here is a Saffrey which I think was balloon quality terylene...
https://abpic.co.uk/pictures/model/M...affery%20S.330