Apologies - as a relative newbie I learn something every day. For some reason I’d got it into my head that BRB referred to Bradford’s (also big and red).
Anyway, woke up this morning with the (fairly straightforward, actually) solution to the ‘event’ in my head. I’d already realised how to interpret the first two letters - just not solved the resultant clue. Still seems a bit of a redundant side mission as it hadn’t prevented me from completing the overall puzzle. But nice to put it to bed.