Interesting that the John Huxley Co. would have advertising chips on the "Square in Circle" mold. I had thought that the mold was owned by the Portland Card Company from around 1947 until the mold was sold to ASM in 1998. That is roughly the range of dates of record cards listed in the 2017 Gaming Table. The Burt record cards posted on the ChipGuide [so far] for orders for inlaid chips on that mold refer to it as the "Portland Card Mold".
I guess either the Portland Card Company did not have exclusive control over the mold, or the Portland Card Company sub-licensed use of the mold to John Huxley.
I've been trying to research who owned and used the "Square in Circle" mold. If anyone knows more about which distributors owned and/or used the "Square in Circle", I would like to know.