Steve they are actually quite common in some ways on eeevilPay.co.uk BUT many are rusted water damaged wrecks or incomplete including the impossible to find back cover panel. Mine is totally complete but the silk speaker cloth is impossible to locate so I opted for satin curtain material as the original has a glossy sheen appearance being silk. They are actually refered to the Philco People’s Set or Radio
http://antiqradio.com/post_philco–people-power.html
The hard to find are the 1937 527 and 537 which are brown. What is comical is these are so called table top radios but my cat is used as a comparison to show how big they are and he is a large cat. I was watching a WW2 documentary the other night and they had vintage film footage showing resistance fighters huddled around a 444 carefully listening to a coded message sent out on the broadcast stations. You are very lucky with yours regarding the power supply other than being a pain in the butt battery radio because this radio is for 200-260 volt mains common over there. To get around this I purchased a Variac with 110volts in and up to 240 volts out. The Herman sets are better as they are 110-240 volts and have taps or settings in the power supply to adjust. My my my what some collectors are Phoolish to purchase, British Philco. Enjoy the ” Big Bullet” as they are often looked for.
