I remember a very busy day at Terminal 4, Heathrow, when staff were pulling out passengers from the long queue to check in for flights which were nearing check in deadlines. The BA person called out BA flight numbers only. Some acquaintances who I happened to bump into were flying on a BA flight to Vancouver, but had a Canadian Airlines' flight number. Not being seasoned travellers they would have ignored the request to come forward had I not pointed out that they were flying BA not Canadian and that this was their flight number.