[Arran]

Philco was an acronym for Philadelphia Storage Battery Company, wanting to expand their market they established Philco companies in various countries around the world, first to import U.S made sets or chassis, and then later to produce sets more locally. The 444 was a creation of Philco of Great Britain LTD, in so they used a mix of imported and locally sourced parts, some sets of theirs had more of one then the other. Incidentally, I did find some service info for the 444, you can thank Phil Nelson for posting this on his site:

https://antiqueradio.org/art/Philco444Schematic1.jpg

https://antiqueradio.org/art/Philco444Schematic3.jpg

https://antiqueradio.org/art/Philco444Schematic2.jpg

Here is some more that came out of a British trade magazine of the day:

https://www.doctsf.com/documents/schemat...CO/269.PDF

I don't think that Spray Nine is too harsh on Bakelite, Bob Andersen uses that quite regularly in his restoration work. I've used laundry detergent to clean Bakelite as well with good results. Chances are that it did have nicotine, or at least lots of grease, dirt, and wax on it if the grille cloth was yellowed that much, smoking was a popular hobby over there just like here, and they probably sat right next to the radio whilst they were doing so.
Regards
Arran