BA stopped some years ago citing the same reason. I can't understand why local area Business pax would today prefer to drive to, and fly from, LHR when it's a much easier process out of Brum. I think the truth might be that many UK firms don't encourage their staff to fly on "targeted" U.S. airlines such as AAL and UAL. A British operator with a code sharing agreement for onward U.S. connections would perhaps do better. Can an A330 fly a full payload to ORD from BHX's runway? If so, perhaps BMI can put one of their spare ones to work.