[Arran]

Automotive hand cleaner like Gojo would probably work well, the cream kind without the grit. It's likely something like an oilcloth, or Rexine, but could be an early form of vinyl. Basically it's like what they covered hard cover books with, though possibly thicker, they usually used on portable radios but in the post war era a lot of companies were trying to put anything out the door, and in the shops, as quickly as possible. I have both a Spartan and a Stewart Warner with artificial leather covered cabinets, it's basically an upholstered poplar or pine box much like you would see under the covering of a portable of the era. I guess they were to fill a gap in the market for a cheaper radio without using a plastic cabinet.
Regards
Arran