I've never met a Peto Scott transistor set, but the position of the controls immediately reminded me of a familiar model -
https://www.radiomuseum.org/r/co_op_defiant_a55.html
Clearly they're much the same inside, and other brands contained the same works - one I used to own was a Magnavox table model,
https://www.radiomuseum.org/r/magnav...tr300300t.html
I'm not sure if Plessey were still producing most Defiant chassis at this point.
Paul