Why would BAA be interested in Stansted ? They have a legal requirement to sell STN, which is being held off only by virtue of judicial review applications that rely on BAA's claim that STN is a purely low cost airport (read Ryanair) while Heathrow aims at the higher end of the market and thus the 2 airports would never be in competition with each other. The last thing BAA would want is for Lufthansa or Air France to open a feeder route from STN to either Frankfurt or Paris, or heaven forbid, Delta opening a long haul route to somewhere like NY
Until the legal appeals process is exhausted and there is clarity over who will own STN long term, short term legal tactics will win out over any strategic growth and marketing.