1. Allow the practice of many American airlines. That is if you turn up early then to allow passengers to take an earlier flight even if on a restricted flight but subject to availability. This can be done at the last minute and unfilled seats can be filled leaving space on later flights for those who purchase a ticket later.

2. For economy passengers at least have meals/snacks available to be picked up before boarding. This way passengers can pick the sandwich or snack they want (e.g. regular, veggie, etc) and in most cases would not have to book special meals. Those who don't want any food need not pick up anything - this will save on food waste and fuel used in carrying unwanted meals. Passengers get what they want and BA saves on time and fuel.