Somewhere in our files there is a proposed specification from Walkers, with annotations by Hubert Hunt (organist at the time), which indicate certain stops 'not to be revoiced'. I'll have a look for it when I've got more time, but I'm sure it includes the Great Small Open and Small Principal, and possibly the Swell Open and Principal as well. There is also an article that Hunt wrote for a local paper which mentions the old stops remaining as before, saying something like 'neither improved nor ruined according to your point of view'. There's no evidence that Walkers did what Willis did at Wells, so I assume the basic chorus ranks sound pretty much as they did pre-Walker (except for the removal of the tierce in the Great Mixture). However, contrary to some old specifications which have either the Swell or Great Clarion (they disagree) as being old pipework, when I did the pipework analysis that's on the website, Cawstons were adamant that all the reeds are entirely Walker.
Paul Walton
Assistant Organist, Bristol Cathedral