I was recently on a BA flight from LGW to Las Vegas. During the flight, a passenger and his son moved to sit in the crew seats on either side of the aircraft in the middle of economy. I think the guy mentioned that he was asked to move by the crew so they could use his seat to rest in (the flight was full).

Is this common? I would guess that this was only an offer from the cabin crew, not a demand. Despite the extra space and legroom on offer, I would not be happy if I was compelled to move to a seat without a table or AV system away from my family. It's also not great for those in the exit room seats, some of whom may have paid a premium for that row, to have another passenger facing them for the majority of the flight.

For those interested in the specifics, it was the individual crew seats facing seats 26B and 26J on this layout:
http://www.seatguru.com/airlines/Bri...777-200B_2.php