On the dutch website www.marktplaats.nl a Wheatstone double bass concertina is being sold.
I never saw a picture of it before.
C. Wheatstone & CO InventorsPatentees & Manfacts Concertinas & Aolas, London nr.: 32454. 8 tones, both sides, original.
The sellers asks € 1.150,00.
Looks like a potential museum piece?