BSA or SBA building at a military airfield in 50s

Hi forum-readers,

Recently I read a crash-report (Vampire FB.5 (WA222) crash at Gilze-Rijen AFB, on October 6, 1951). The text mentioned that the Vampire collided with a BSA (or SBA?) building shortly after take-off. The building was supposed to be some kind of navigation guidance (a beacon, hence the “B” in the abbreviation?). Who knows what BSA (or SBA?) stands for?

Regards,

Benno