when I flew LHR-PHL last week, the checkin agent directed me to the BMI lounge, which I have to say was pretty bland an unimpressive (the upper level). To top it off, either there is no air conditioning or it was broken, and the place was sweltering, with fans being used to cool it to little effect.
It was not until I left and saw the sign for the *A lounge that I realized there is another one you can use, and I went there before boarding to see. It has a much better selection of food, although it was a bit crowded, and some of the lounging areas seem a bit, well, sterile. But even so, it was better than BMI lounge.