Its really curious that BHX doesn't or cannot support a three-class Emirates operation when Glasgow for example can.
Birmingham and the Midlands (including the East Midlands) has and continues to gain major businesses that you might have thought would attract passengers with big corporate travel budgets that would make a first class operation work. Perhaps cramming passengers that connect to the sub continent and further afield into 'cattle class' so they can bulk out connecting flights somehow makes more economic sense?
For sure with the rise of Edinburgh as the economic powerhouse in Scotland Glasgow would have smaller front end market than BHX.