Originally Posted by ozzie
Passenger Number Reference - a fancy name for a ticket !!
Very pedantically, it's actually the Passenger Name Record - the airline's record of your booking with them which is called up against your name. The booking reference is often called the locator so that the airline can locate your PNR. It's different from the ticket, which may after all be paper - you have a PNR even if you're travelling on a paper ticket.
Originally Posted by tealeaf99
Because the LHR-GLA is an intra-UK flight, you do go through customs at LHR (and not in GLA). You do this just after you have gotten your BA boarding pass, are exiting the Flight Connections area, and are heading to T1. This customs check is usually quite fast.
Technically, you only clear immigration at LHR - where your passport is checked and stamped if necessary. You actually clear Customs at GLA, but reports are that Customs at Scottish airports are very laid back about this, often to the point of just letting uncleared bags go straight out onto the belt with domestic bags and no requirement for you to make the implicit declaration of walking through the green channel.