B.A. have just announced that rather than wait until 24 hours before flying, customers can now pre-book their seating at the time of purchase. The downside is that they are charging £10 per sector, so £20 per return, or more likely £40 if flying through London from Scotland because a change of plane and therefore extra sectors is required.
I hope this is a spectacular failure. If not, then all scheduled airlines will soon be charging for something that currently gives them an advantage over charter and no frills airlines.