Yup, looks like it is a three class now:
From my corp web booking site:
Flight 297 J9C9D9I7W5T0Y9B9H9K9
London, England (LHR) 11 Nov, 2006 12:45
Chicago, IL (ORD)
11 Nov, 2006 15:50
Seat map shows four rows, so deffo a three class jobbie.
Suggest you call BA pronto as they should be able to put you on one of the other flights with F (the other two are OK with F available).