WestBrit,
This is exactly the point. Without a competitor for LHR route, BA could easily move to BFS and have much greater flexibility than BHD can ever offer, and at a much lower cost, as you point out, later flights, larger aircraft and higher utilisation, more flexibility etc.
However, their strategy of being at BHD has been sound to date, and lets not forget bmi moved their operation originally to BHD as a point of difference to the high level of competition on point to point ex BFS by low costs airlines at that time....
We ought not open up a debate about BFS V BHD as it is at best a futile exercise....