Can anyone help identify these leg irons?

Hi all
New to collecting, well ok, been collecting over 6 months now.  I came across a legiron I thought was a plug 8.  The item arrived and its weird so Im asking if anyones seen it before?
The key is stout and fabricated with 4 heavy stubs that fit between what appear to be wards in the lock tube.  I dont think its cut down threads because the wards inside the locktube are in pairs and equidistant between stacked wards.

I see no indication that it was a standard plug 8 that has been altered.  Im attaching pics.  Does anyone have any idea as to what this is?
Many thanks

I had discussed this pair with another collector when it was on eBay. It seems to me that the key head is that of a house key or similar and the 4 sided end has been made to fit the four sided nut. That's the easy part. I can see from your images the file marks where the 4 "Wards" were filed out of what was probably a thread. It also seems that the "wards' although equidistant, are at slightly different depths as if they were once threads. Obviously, you have a better view of it, but have you tried screwing in a LH or RH threaded key to see if it functions that way as well? That is the most logical explanation because those wards would only stop a flat piece of metal being used as a key.

Hi
Yes
Ive tried all my plug Keys small and large right and left hand threads.