Rob Parsons kindly shared these images with me. I’m sure many of you will have seen this pen before, in slightly different configurations and with different names.
It isn’t quite a fountain pen, in that it needs frequent intervention by the user to keep the ink flowing. It’s more of a dip pen with a reservoir.
Sometimes this pen appeared with its own fountain pen style nib, others, like this one enable the fitting of dip nibs.
An interesting sideline to fountain pen history.
Goodwriterspens's Blog 
very interesting and I’d guess a scarce item now – thanks to Rob for sharing – does Rob have an indication of manufacturing date please? Although dip pens not normally my scene I acquired quite a posh one recently which incorporates a No. 6 C.S. 14 ct. nib (whatever a No. 6 means) – though it may well be that C.S. didn’t make the main unit. It also boasts an integral pencil.
May I send it to you Deborah for showing? It really is quite a nice one:-)
They turn up not infrequently under various names but the same design. 1920s or 30s, I think, and really a cheap alternative to the fountain pen.
I would love to see your dip pen/pencil and I will post about it here.