Further to Bob's post, I came across this site:
http://www.courtleet.free-online.co.uk/BMTC/history_sport.html
which contains a brief description of the Rat Pits.  It also has a
picture which shows the rats piling up in the corners of the pits.
Finding no escape from their pursuers the rats would attempt to hide
under each other.  This apparently, was the usual strategy employed
by the unfortunate rats.  Of course, this could only happen in a
square pit.
 
In a round pit the rats formed into smaller groups.
 
For further information see
http://www.staffordmall.com/stoutheart-rats.htm
 
George
[Posted in FML issue 4074]