A Waterman prototype surprise

Many years ago I acquired a group of prototype Waterman Hundred Year pens, all of first year design but most in colors that never made it into production. Recently I finally got around to cleaning them up for proper photographic documentation, and inside the pen shown above there was an interesting surprise.

There was actually a bit of a clue beforehand -- "LEW" and "X" and "I" scratched into the bottom of the feed. Plus of course the pen's completely nonstandard color, an opaque metallic blue.

Nonetheless, there was no anticipating this. Incidentally, several of the pens in this prototype group came with #7 keyhole-vent nibs. As pre-production examples, they might well have been put together before nibs with the Hundred Year imprint had become available.

And here is a more complete view of the feed. At some point I'll have to look to see if a patent application was filed. 

While some of the pens in this group are pristine, such as the light green metallic example shown above, most had been carried and used, including the blue pen. It was undoubtedly a working prototype and not just a material trial.