Delta still has a ton of tail #'s ending in NW and AT.
Still, the real 787 tail numbers are N780HA - N783HA. Perhaps they meant to put N785HA for a future delivery?
N705HA is already
registered.
Or as someone on another board mentioned, could be a nod to an action in 705AD when land was granted in Cornwall as a metaphor for BA granting AS a landing slot? LHR is not in Cornwall, however.