WE went through LHR on the 6th August and I noticed the lunchtime PMI was cancelled. We also have friends whose flight back to LHR was cancelled last Saturday and they were re-booked to come out of there on Tuesday. Even as early as May, BA cancelled a SOU-PMI flight that friends were travelling on at very short notice. Some pax were re-booked on the evening LGW service, but they had to get themselves to LGW and claim the taxi back.