Its a horrible yield killer for BA.
Even if it is mildly profitable. They charge the same fare that they get for 1st class on a 747/777. If you took those passangers and put em on the subsonic fleet the subsonic fleet would be wildly profitable.
What the concorde does is skim the high paying pax off the subsonic fleet, thereby destroying the yield. When the price of fuel spikes, the economic case for concorde gets even tougher.
Cheers
Wino