Discussion on which lounge they could use in 3...2....1....
(There's only one in the main terminal, the Escape lounge
)
There's a fast track at STN which works very well, and Air Berlin Topbonus higher tiers can use it when flying AB which is an example of Oneworld status. So BA could certainly pay for it if they wanted to.
AB, being tight-fisted, don't pay for any other OW elite to use the Fast track for their flights (as far as I know), hopefully BA would allow any status passenger on their flight to use a fast track.