I asked this exact same query last year, and these are copies of the
responses that I had at the time, see below:
Science Museum: "I don't think they are here - not going by our catalogue.
Although we do
have a couple of collections of stones....could be among those perhaps?"
Royal College of Surgeons: "had the same enquiry a few months ago! We don't
have them here, and were unable to find out were are."
As the Museum of London recently had an exhibition about Samuel Pepys and
displayed a representative bladder stone from the Worshipful Society of
Apothecaries, it seems that they didn't track it down either. The Curator
of that exhibition was Hazel Forsyth.
I hope that this is helpful.
Royal College of Physicians
11 St Andrews Place
London NW1 4LE
Tel: 020 7935 1174, ext 510
Fax: 020 7486 3729