Originally Posted by
Fruitcake
I am afraid, dear
HilFly 
, that although this may not be BA policy, it is often what happens in practice IME. LGW is very good in most respects but the timings for boarding on the screens are often very awry.
True! But in my experience it usually works the other way. Lounge says flight boarding; five minutes later at the gate arriving passengers are filing off the awaiting aircraft