The first Summit brand was made by James Dixon Ltd. These are rather rare nowadays but well worth looking out for, though that may take a lot of patience with no guarantee of eventual success!
I think the quality shines out in all of these pens. Very satisfying design and pleasing chasing. The lever filler, in particular, is a splendid pen, the equal of anything of its day. The safety pen, too, is an admirable instrument. The biggest surprise for me is the crescent filler, something I never knew existed. Any crescent filler is going to be reminiscent of the much better-known Conklin but the design is equally well executed here.
These Summits are clearly products of a company in the first rank of pen manufacturers. It is pleasant to speculate about what they might have achieved, had the company lasted longer.
Many thanks to Andy Russell for information and the excellent photographs.
Goodwriterspens's Blog 
Thank you for the interesting article and pictures. They cdrtainly were first class pens, as it was the case with the later Summit pens, made by Lang of Liverpool.
Just a brief note about the first pictured pen: some exemplars of the type were later acquired by Lang and sold under the Summit label, after removal of the J. Dixon name. A few pictures of an exemplare of these later pens here: http://forum.fountainpen.it/viewtopic.php?f=8&t=11179#p135995
Alberto Casirati
Thank you, Alberto. Another addition to my knowledge of this fascinating brand!
There are a number of anomalous UK crescent fillers now known from the early 1920s, including several with the same ARC logo on the crescent. Among these are two further examples of the James Dixon Summit, one of which is an own brand pen imprinted Autocrat. Autocrat were US-based motor manufacturer operating in the UK in the early 1920s, and the pen came down to the present owner from his grandfather, who was employed as a salesman in the motor trade. There is also a Conway Stewart-made ‘Empire’ crescent-filling pen, and most intriguingly, I came across a reference on the internet to a crescent filler imprinted ‘A.R.C. Pen Co London’, located (from memory) in Tasmania. I would be interested to hear if any reader knows about this or a similar pen, as I have so far been unable to find any record of a company with this name.
All very tantalising!