[Arran]

It's most likely polystyrene, but I have seen Bakelite cabinets with a rosewood look to it as well, Phillips made some sets that way. My guess is that it could have been made at any point between the late 1940s to the mid 1950s, I have schematics for similar clock radios that span that time period. I think that there was even a Philco clock radio or two that had a similar layout, Telechron clock and a thumbwheel dial for the radio at the top. There was even a clock radio with a similar design that was simply marked as "Telechron" but I doubt whether they made it themselves.
Easiest way to tell Bakelite apart from polystyrene, if you aren't familiar with the feel of the two materials, is to heat up a needle and press it onto the inside of the cabinet some place where it won't show. The hot needle will melt into Polystyrene but will not melt into Bakelite. I have never tried this because I can tell just by weight and the texture, plus Bakelite is more rigid and will not flex as much.
Best Regards
Arran