I called around and took the following notes:
A long sole is the full sole, half sole is just replacing the part that contacts the ground, not the waist.
£89 long sole, £31 half sole, £11 for postage one way, if you don't want to go to their several locations outside central London. Someone posted that they do central London pickup, but I called and they said no.
£85 long sole
£111 long sole
Tony's, as recommended by The Shoe Snob
£38 half sole, £68 long sole, channeled sole £5 extra
I went to Tony's and had them do the long sole and channeled, took around 4 days. Upon receiving them, there was about an inch of stitching still visible around the waist. After a few miles of walking, they looked like this:
Stitching is now visible, so the channelling was pretty much useless. The original soles on all my goodyear-welted shoes are channelled and even after a hole was worn through the sole, the stitching was still not visible.
It's not a big deal as I can deal with exposed stitching but I think I'll try John Rushton next time.