Several people have asked for the chronology and suggested reading order for the books by A.J. Hall. So here it is:
Queer as Scent and The Mark of The Beast can be read in any order.
For an alternative view of the chronology you should also have a look at Geoviki's web site.
It has an excellent unofficial guide to A.J. Hall's fiction, over at:
www.livejournal.com/users/geoviki/6442.html