This has been a very interesting thread, with many Listers chiming in from their experience.
Clearly the Ebay Braxton has raised a number of queries in observers' minds, such as the vey slack head angle, the relatively high step-over height for a smallish frame, the steepish seat angle...
Very evidently this frame is very much a custom one designed to respond to the needs of a customer who possibly had back problems, did not want to be too bent over and liked to ride in a relatively high position...and Full Marks to Sam for giving it his best shot...It's not the easiest frame to design and might just provoke a few compromises. I remember that in the early 80s a well-healed ( meaning not short of money) customer asked me to design a bike not dissimilar from the Braxton.
Now..like many frame-builders in the North of England I did not see too many well-healed customers coming through the shop doors, so I was very eager to please. This chap had no deformities or health problems that dictated a higher riding position but he was, he told me, an ardent bird-watcher, and he loved to cycle in a leisurely style along the Yorkshire Dales watching birds. For those of you who have not visited this area, the Dales are well-known for the high random stone walls that border the lanes and surround and delineate the farmers' fields...hedges are more rare. Therefore this chap needed to be sitting quite high to be able to see over the tops of the walls and into the fields beyond. He stressed too that his cycling involved negotiating quite a lot of small strems that crossed the roads and puddles in the wall bottoms...so braking would be an issue.
The bike was duly built according to his vision, the customer sat high and perched along the length of a bike with quite a long wheelbase..fork trail was designed to provide predictable handling and cornering..and braking was supplied via a pair of SACHs drum brakes..and I seem to recall that the gearing was that wonderful - for birdwatching bikes that is - Huret Orbit 3 x 5(6) derailleur internal hub system..because the customer wanted an ample selection of gears but did not relish coping with, he warned me, one of those 'double-clanger things'that the chain is always dropping off' A sign-writer friend neatly painted 'Bespoke Ornithologist Model' on the top-tube.Unfortunately I did not get a rush of repeat orders - just one, I think..nor did it attract many more well-healed customers through the doors.
The Ebay Braxton appears to have a standard, perhaps slightly lower than standard bracket height, so the higher than normal stand-over height - 32" - measured vertically above the bracket must be due to the fact that the head tube is longer than normal and the top-tube is sloping up from back to front of the bike. However for a bike that, with brazed-on rear pannier frame, appears to have been designed for serious touring, the bike has quite large clearances under the fork crown and the rear bridge. However this might be because the wheels in the bike, shod with 25/28mmm tyres might not be the original ones. The longer fork blades and seat=stays would push the bike higher off the ground. The very long chainstays - at 18" longer than those on my 24" Reyhand Randonneur - coupled to the very long front end (due to the shallow head angle) will give the bike a very long wheelbase which would tend to make the bike's ride very comfortable..but quite sluggish I imagine. Due to the seat angle being slightly steeper than normal, the rider will be pushed further to the front of the bike( Intentionally) and he/she will very much get the impression of being mounted amidships, this position giving the other impression of sitting in the bike rather than just being perched on it. If I had made this frame I would , in recognition of its slower riding characteristics, have called it my "FESTINA LENTE" model...'meaning " Make Haste Slowly" and it would have become one of my Latin Series.
Settle -in -Ribblesdale, UK