Matt
15 mins in a f1 car (no speed checks on the M69, M1 not so forgiving!)
Even CVT - BHX will take a good 25 mins (lots of cameras), but the argument often used is Cov BR - B Int station is just 10 mins.
So what? Baby & Ryan both @ EMA and BHX. Ryan now gone into allsorts of cities where they have used both (or even all) airports.
I would generally assume that an airline at BHX is less likely to add routes at CVT, but they could still add a different range of destinations. Jet2 at MAN & BLK, so would CVT really be out of the question?