I took a 777 lhr to washington a few years ago,empty aprt from we 2 pilots.No passengers due to lack of cabin crew so they cancelled that sector but the aircraft was still neede for the return flight. Ohh and cabin crew do make a dive for the bunks asap. The 747 is used to go to cairo,bunks are fitted to the aircraft and what is interesting is the bunks are prepared with pillow cases and blankets with the intent that the dearies have time to go to bed!