OK - so this is a correct and interesting unusual Parker item. I am still a little perplexed by what looks to me like different chasing on the cap and barrel. But that is not really important to the discussion of the clip.
Now that I have a name for the clip, I have some "quick and dirty" Google results
There is a patent date on the clip in one item on ebay in the past
I just started looking at that patent date and found some cute things for clipping pens to pencils, but not for this clip yet.