It is thought that Radions had closed by 1930/31. This came about because the
price of new valves from the major makers was reduced leaving Radions new valves
uncompetitive and their repairs uneconomic.
The valve pictured is a repaired R5V triode, which was a development of the 'R'-type valve. It is a bright-emitter valve; that is to say that the filament glows brightly like a light bulb. Later filaments were coated with a thorium oxide layer, which allows electrons to 'boil off' at a much lower temperature, so the filament could run at dull red heat. This gives superior performance with much longer filament life.
The filament on a bright-emitter valve normally either melted or simply fractured due to the considerable thermal expansion and contraction. Wireless sets incorporated 'filament rheostats' to allow the current and hence temperature to be reduced to the point where adequate performance could be obtained - wise users kept the filament current as low as practical, but a multi-valve set still gave out enough light to read by! I expect that most of Radion's repairs were filament replacements, followed by re-evacuating and sealing the glass envelope at the top of the bulb (see the spike on top in the picture).
Valves in the 1920s were poor performers by modern standards; we used a technique known as 'reaction', which is a form of positive feedback, to make the receiving tuned circuits get very close to oscillation, thereby increasing the amplification. The 'wooden box' and 'copper box' receivers using this technique can be seen on another page.
By this method, even a poor valve could make a relatively good receiver; far better than a crystal set, which has no amplification at all.
If the 'reaction control' was over-adjusted, the valve would oscillate and behave as a transmitter, interfering with all the sets in the vicinity.
It seems from my experience that Radion's used a fair bit more red phosphorus as getter than most contemporary manufacturers. Their valves (the very few that I have seen) are considerably more densely coloured than many others that used phosphorus - most, if not all of them, in the 1920s. By the 1930s, most valve makers were using magnesium, which gives the more usual 'mirror' appearance to the glass.
In 1918 Messrs Crowther and Osborn established a factory
in Lowerhouse mill to manufacture household electric lamps
under the name of Sceando, pronounced C-and-O. They also
had a factory in Bredbury where they made the special glass
required, and at Lowerhouse they assembled the bulbs.
This company lasted only until 1923 when it was wound up
in the face of anti-competitative action by the larger lamp
makers claiming breach of patents.
One of the driving forces of the company was Mr J. W. Pattison,
who went on to found Radions Ltd., described above, and,
later, Lustrolux, described below.
J. W. Pattison joined with partners and set up another company, Lustrolux Limited, also in Lowerhouse Mill. This company not only made and repaired valves but also manufactured household lamps. Valve production at Lustrolux continued to about 1934/5 and domestic lamp production continued into the war years.
W. Pattison's son, W. J. Pattison, began making vehicle lamp
bulbs within the Lustrolux factory, principally for the commercial
vehicle industry, and this became Associated Lighting using
the trade name 'Alite' (picture left). This business was
developed after WWII and by the early 1980s supplied
80% of the UK automotive industry demand for vehicle light
bulbs, but no longer from Bollington.