I have recently been sent a schematic wiring diagram for an experimental amp called the "Fenton-Weill Studio 20". This was drawn in April 1959 by a company based in Essex called United Vista Industries.
The amp appears to be a 15 watt approx combo design, with just two inputs, each with a volume and tone control, and utilising a 15" loudspeaker. The valve line-up is 1 x EF86; 1 x ECC83; 2 x CV4043 (or 2 x EL84); and 1 x EZ80.
Presumably, United Vista were being employed by Henry Weill for design work prior to him commencing amplifier production sometime around 1960. I have to say that this is the first time that I have heard of the "Studio 20". Perhaps it never got off the drawing board? It's yet another of life's mysteries!