The economy seating configuration is going to be 10 abreast according to the BA article in Airliner World. That's one pleasure I will not be looking forward to.
That must be a mistake. The max seating the 787 will take is 9 abreast, Boeing originally proposed it to be 8 abreast.
The 777 is wider than the 787 and BA have 9 abreast on the 777.