Although not referring to BA specifically, I'm with jackieofalltrades. It does depend on the airline, the type of aircraft and the flight concerned.
As one example, at the time of booking on a recent flight with KLM, my best option (in Y) for a window was 14F. On boarding (last to board) I noted that several rows nearer the front (but in Y) were empty. I believe that one reason for this is that the division between Y and C is flexible and the earlier one books the less choice one has because at that point in time the final C / Y configuration is undetermined and thus a number of rows will not be open for selection until nearer to departure day. Of course, long haul, with fixed cabin layouts, is another matter. Here again, I do believe jackieofalltrades is correct in stating that "prefered" seats remain blocked for Premium FF pax and are only released shortly before departure day.
Last edited by Hotel Tango; 9th Feb 2013 at 06:35.