bmi regional's core business is still business passengers. bmi baby is the low cost division. bmi mainline is the LHR division. Rather confusingly since last summer most domestic routes out of LHR are single class offering baby fares. bmi mainline "pays" regional to fly its skinny routes out of LHR during the summer so that airbus's are released for charter work or to replace a broken baby 733. Regional also do summer charters to Sardinia/Corsica/Solvenia and the odd one for Man U and Chelsea. (very popular with the cabin crew strangely).
Confused?
You should be.
My guess is after Sou-Ams, regional will start competing with flybe and bacon on the Sou - Man/Edi/Gla. I doubt if you'll see a baby 733 down there. Isn't BOH the airport of choice for low cost airlines in that neck of the woods?