J and D's Vintage Pens - "Missing pens"

appologise for the quality of this advert which itself is a photo-copy of the original. It shows several series of pre-1920 Conway Stewart pens, almost none of which have I been able to document in other people's collections. It would seem that for several years after the Conway Stewart Company was established in 1905, pens were manufactured for them by other Companies, and I have two "no number" Conway Stewarts that were almost certainly made in the US to prove my point. Most of the pens in the advert are eye droppers but the pump fillers (Nos. 1, 4 and 6) are exceptions, and to illustrate this I show a W.H. Smith pen from the same period "exploded"to show the inner piston used to draw the ink into the barrel. Page 1 of early advert

Early W.H. Smith Pump filler Page 2 of early advert

Since I wrote the above rubbish in the first version of my site, my opinion has changed but the mystery still remains a mystery.
Reading an article by Steven Hull in the WES journal of 1960 set me on the right(?) course. He states that from 1905 until 1920 when they registered their trade-mark "The Conway Stewart", the company was making pens for other companies, and that is why no early Conway Stewarts are known. Such pens would have been eye-droppers and the only ones he knew of when writing his article were equivalent to the Duro No.1 apart from the ink pencils and all these were clearly from the late 20s. The above advert seems to contradict his conclusions, and I would think that the Company was making pens under its own name since 1917.
So I still think these pens were the first pens manufactured by Conway Stewart under their name (without registered trade-mark) between 1917 and 1920. Any no-clip, "The Conway Stewart" pen with a straight or spatula lever probably dates between 1918 and 1925 when the No. 235447 patent for what I now call the flange lever was granted.
Now for the pens with clips: take for example the earliest No. 206. This has a clip fixed internally through a slit in the cap without a logo plate, and this feature is common to other pre-1925 numbered pens such as the Pixie 353. However, I have two un-numbered pens with the imprint on the cap and the same clip arrangement, but these clips are quite different in shape from those on the numbered pens. Furthermore, as if by coincidence, I purchased both these pens in the US. The imprint does not say "Made in England" as the other pens do, but states "Conway Stewart & Co. Ltd., London Eng.". All this leads me to believe they were made in the US for Conway Stewart, and then this clip system was copied by the Conway Stewart company in the UK. This I mentioned in the above statement. I even have a No 270 pen which has a US type clip with a Whal type roller ball at the end, and US Pat on the clip itself!
David Wells is getting these patents sorted out for both pens and pencils and should publish his findings shortly in the WES journal.