The GLA service had exactly that philosophy, with the BD14 LHR-GLA late evening being codeshared by frankly everyone and their granny! Still couldn't make money, also BA's LHR-BFS was always pretty full but the revenue went to long haul due to "too many" connecting, so the route was a loss maker !
Internal accounting can be a nightmare, but I wonder if bmi feeding STAR at LHR is really worth the candle. Indeed strategy has moved to more point to point flying on behalf of STAR partners.