even on the 2200 departure from Heathrow
That's just reminded me of one occasion when having left home at 6pm, I arrived at LHR around 9pm because of traffic on the M25. I managed to wolf down a meal in the lounge and settled on-board at about 21:45. Believe it or not, at that time my company (large well known international chemical group) used to give us a travel pack with, amongst other things, sleeping tablets in it! I gratefully washed down a couple with my champers and looked forward to 10 hours or so of useful unconsciousness as we pushed back. About a minute later we were brought back to the gate and unloaded because of a technical problem. We eventually escaped at about 2am in the morning by which time the tablets had worn off and I still had to face the journey. I believe that was a record 33 hours of travel door to door.
Never, ever again.