I never clip a pen to shirt or jacket so what is the clip for? For me, in use, it has the benefit of keeping the pen from rolling off the table. Otherwise, it’s a means of advertising the manufacturer and many have been the brilliant designs devised.
The earliest fountain pens did not have clips. The pen was desk furniture and there was little thought of carrying it on one’s person. Indeed it would not have been wise to carry some of the early eyedroppers; fine writing instruments on the desk but an accident waiting to happen when attached to clothing.
First came accommodation clips. Most of those available “over-the-counter” were quite clumsy things, brass or white metal plated with gold or chrome. Ones made by pen makers were better: Mabie Todd’s “Clipper” is light, elegant and bears a durable finish. All accommodation clips have their problems, though. They tend to overbalance posted pens and their finish is often not durable, spoiling the effect of the restored pen. Tightly fitting clips on hard rubber pens, in place for a century, can be tricky to remove. When caps are fragile the clip has to remain in place.
Some manufacturers, Mabie Todd and Conway Stewart come to mind, made “pockets.” When new these were a good solution but after decades in drawers many have rusted inside and will scratch the surface of a pen. They should not be used unless the interior has been polished clean.
If you happened to be writing in public – as people do with their laptops today – that provided the manufacturer with an opportunity to advertise that it was his pen that you were using. Whichever brand that was there had to be some means of identifying the pen. Simply engraving “Parker” or “Conway Stewart” on a pen was something but not much. Someone wishing to know which pen you used had to get close enough to read the script. Parker, like half a dozen others, chose the image of the arrow. It qualifies as a good signifier for a fountain pen in a variety of ways. The feather is common to the quill and the arrow. The fountain pen and the arrow have some similarity in shape; both are long in comparison with their breadth and both have a sharp business end.
The Chinese saw the benefit of the readily-identifiable pocket clip and made use of it but not in the most honest of ways. The Hero 616 appears to have been intended to be passed off as a Parker 51. The Wing Sung Vacumatic clearly isn’t a Parker 51 – the ink view window makes that obvious but the wish to be associated with Parker through the clip remains. The Chinese seem lacking in imagination. Apart from Lamy, the only pen they copy is Parker. There are many other famous old pens with recognisable clips that they could copy!