Firstly I'd like to say a huge thanks to everyone who's sent me
references, advice and encouragement.  Thanks for the generosity of your
responses (even if I haven't replied to them all yet I really appreciate
you taking the time and trouble).

As suggested I've had a mooch through the archives and came up with a
reference mentioned in a 1994 post:

Bryant, Douglas D. "A Stylistic Approach to the Study of Privies",
American Archaeology 7.1:66-76

According to the post the journal was 'obscure and defunct' so the
chances of me finding it over here in the UK is about the same as
finding a bee playing the ukelele!  I checked our inter-library loan
system anyway but with no success.

What I'm hoping is that someone out there might have a copy and be
willing to fax it to me (or mail as an attachment although it would
necessarily be a large file).

My fax number is +44 870 0523464
(if there are any problems with this number please let me know and I'll
pass on the fax number of the University Arch Dept where I'm studying).

Thanks to you all again,
Alison Jackson-Bass