Originally Posted by
continentalclub
G Class is used for groups, but also for various other types of booking including staff (Hotline) and connecting travel.
It is also used by avios.com (chavios to use its term of endearment here) in the UK for their redemptions, so when BAEC doesn't offer a redemption, avios.com can often offer availability if G buckets are on sale. Probably deserves a thread in its own right.