I was a little hasty to post as I've found it now.
If anyone else, searching in future, has problems with Access 2002 speed in a highly relational database then make use of this property.
As Access97 doesn't have this property then Access97 databases can run faster. Access 2002 databases with this property set to [Auto] (which is the default ) will become slow, especially when split into a front and back end.