In reply to Tree:
The walkway isn't exactly wheelchair friendly but isn't hugely dangerous/ taxing if you pay attention to what you are standing on: In some places the walkway is a single layer of unreinforced concrete <1" thick which obviously isn't very strong, but these areas (at least on the bits I have been on) have been pretty easy to spot and avoid. There is a safety cable fixed to the wall on most sections but it is of variable quality, some sections probably wouldn't support a damp towel but thankfully seem to be on much more solid sections of the path. From what I've seen the good cable is generally indicative of a dodgy bit of path, presumably some sort of "danger averaging system" is in use
Some of the beams are a little more exciting for shorter climbers as they can be a reasonable distance from the wall.
There are definitely sections of cable which wouldn't hold a fall on a static lanyard, although they seem to be in areas where a fall is less likely so it comes down to a personal risk assessment. I used a few lengths of dynamic rope with slightly loose (but stoppered) knots in the hope of adsorbing some of the shock if I did fall off. When I did it the most risky bit was the group wandering about and setting up an abseil off the end of the walkway by the first railway tunnel as they were directly above the heads of people traversing below and the path there is pretty dodgy.
