HM, querry high yields on short haul? What about thge added costs of the CAT Lounge? Transport Costs? It goes on and on which must detract from your High Yield. The out stations don't have that. also LGW is needed by BA not only to stop Easy from gaining too big a foothold but also to provide our One World alliance partner "American Airlines" with a feeder network.
Nothing is simple, nor straight forward LHR is not the be and end all. Though there are those in BA who consider it so.