LoL...yes, Robert. I am among the Americans that knows the difference between the rifles. I also have a "Smiling Tiger" Mk.III.
I can't tell you any history on the Thai marked No. 4's. I would presume they were post war due to the occupation of Thailand by the Japaneseduring WWII. The only reference I have found is in the back pages of "The Lee Enfield"....in the latest edition it is on page 588. I don't know what page it is on in the previous edition as I loaned that book out.
Ian has a very small paragraph with a picture of each of the marks I have shown and reads as follows.....
"Savage Stevens Lend Lease No.4 rifle with Siamese markings. The "Juk" mark has Hindu origins, a "weapon of the gods" and was originally used on weapons of the royal bodyguard"
In Skennerton's "The Broad Arrow" he calls the small receiver marking a "Chuck" (Chuck-ree) and the stock marking a "Chuck" No indication of how many or when.
The full name if you wish to search "google" would be "Siamese Chakra" or "Sudarshana Chakra". You will see many images of it and references to the Chakri Dynasty when doing so.
I never found, or rather, looked for any more information than that.