I have not been in a BA lounge and seen this happen when faced with the same circumstances. Even Z7 (Zimbabwe Express Airways) kept their domestic lounge open for roughly two hours after their last flight (which was cancelled) was due to depart, until all of of the passengers were accommodated by customer service agents. Perhaps in the US lounges are run as businesses, but in this country, and most of the world, they are a product and an integral part of an airlines customer service to premium and/or frequent travellers.
MapleLeaf - I am not sure why you too seem to dislike me now. Is it something specific?