Just returned from abroad having used the services of T2 LHR. Arrived for outbound flight in the early hours of 15 December to find utter chaos in the terminal. Pax almost queueing out the doors. Weird snake like queues in multiple directions. Numerous pax becoming irate amid concerns they might miss flights. There was some form of system where staff were announcing imminent departures and relevant pax were pulled from queues. When my turn came was sent to front of queue to use self service baggage tagging. Bag eventually checked in, picked up boarding pass and whisked through security via fast track lanes. Arrived at gate as flight was boarding. Fast forward 12 hours and discover my checked in luggage had not made it my final destination! Luggage finally arrived a full week later as for some unknown reason it was not loaded onto my flight and only actually left LHR 3-4 days later. Utter shambles!