I've obtained the following additional information from Sothebys. Not completely helpful, but better than nothing. I've also asked them to find out what teh "home" keys are.
"Lot 309: A thirty-two button Anglo-German concertina by C. Jeffries,
London, circa 1900
bellows a little rubbed, buttons have a tendency to stick, hand straps are
not original and one is broken
Pitch: A = approx 440Hz
Lot 312: A thirty button Anglo-German system concertin by C.
Jeffries, London, circa 1900
syphoning extensicely, light rubbing, left strap a replacement, both strap
screw replaced by modern Philips screws but the original are in the case.
Case lid and handle detached
Lot 313: A thirty button Anglo-German system concertin by C.
Jeffries, London, circa 1900
leatherwork rubbed, f sharp/g sharp button syphoning, metalwork slight
corroded, straps replaced
Pitch: approx 435Hz."
All the spelling and grammar mistakes are Sothebys' own
Alex West