Singapore Airlines, Cathay Pacific, Emirates Airlines, KLM, Lufthansa, SAA, ANA, AAI, Atlas, etc. all employ British citizens that are current and typed on the mentioned aircraft. Simple powers of logical deduction tell me that perhaps BA are trying to entice some of these blokes "home." It is perfectly conceivable that some of these chaps may have gone to work elsewhere when BA was not recruiting, and may now love an opportunity to join them.
On this particular issue of "foreigners", anyone taking a deep breath, sitting back and giving it due thought, will come to a similar conclusion and that is: this particular sentiment has caused almost more problems worldwide than differences amongst religions has. It's not worth getting your t1tties in a tangle over and what's more, as pilots, shortly after take-off we all become foreigners!