The poster mentioned problems with BMI when connecting with Virgin. I have had very similar problems. I had a single itinarary through ticket from regional to usa via BMI to LHR and then on to JFK with Virgin. Could not for the love of money get through checked. All I got from BMI staff was "we don't through check bags", despite my repeatedly pointing out the nature of my ticket -which was confirmed by both BMI and Virgin as being a single itinerary and therefore could be through-checked!!
It put me off using Virgin again,when connecting from anywhere other than LHR itself.
BMI are a budget airline now. Expect very little.