If someone on this site bought that diecut wadhams flange on ebay it's a fake
size is the same, mounting holes & graphics are different from the "Real McCoy" (1st picture) .. ...
ebay aftermarket version (2nd Picture),
https://www.ebay.com/itm/Wadhams-Motor-Oil-Porcelain-Flange-Sign-/154416470654
I also noted the font used on the flange is way too modern for this period of sign.
I have an original and yes way different