Do you have Clive's "Inglis Diamond" book? Because I don't and we need this book to check following theory. Many ppl here have it and hopefully will chime in.
From what I know - Dieudonné Saive (the guy who actually designed HP) and and Rene Laloux from FN arrived to Canada to help to set up manufacturing with original FN technical documentation. What it tells me that first pistols made at Inglis had to have exact look and features as FN made pistols, including front sight. For example I know that early Inglis HPs had round barrel cam, that probably was result of using original FN drawings that for some reason lacking updated to square cam (FN changed to square cam in 1938, unlike popular belief there were no issues with round cam at all, but at certain stage due to one of FN customers' request square cam was accepted and recognized as change worth keeping). Usually when manufacture is adopted by new company and/or for new customers there might be some simplifications/improvement changes. It looks to me that "standard" Inglis front sight is simplification from original design, i.e. looking crude, but less machining operations required, so cheaper to make. I suppose if Clive's book has pictures of the very first slides made at Inglis we might be able to see same pattern of front sight.
Now, do Chinese enrolled slides constitute early slides? Then this fact supports my theory that your slide is early.
P.S. Holly molly, I totally overlooked the picture of barrel in your original post. Man, you just have very early Inglis HP, with round cam and original FN style front sight. I think along with early barrel my theory is very conclusive. Congratulations, Nick, you found very nice Inglis, very special.
A friend of mine has a copy of the book, was hoping to borrow it so i could give that part a read. What got me looking again was actually because he was buying a Inglis with Chinese script and he showed me some pics of it and i noticed the front sight, decided to do a bit more googling and found several more, all Chinese script models. I have yet to actually find any pics of an inglis with this front sight without the Chinese script.


















































