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.