In size terms a 787-10 is roughly the same size as an A350-900.

For most of BAs routes there just isn’t the need for an aircraft as capable as the A350-900. The 787-10 Is ideally suited to the 7-10 hour routes, with the longer range routes ultimately being performed by either the smaller 787s or the larger A350-1000s and 777-300s.

It’ll be interesting to see whether there will be any fleet rationalisation when the final 747 and eventual 777-200 replacement is announced.