BA, Booked on Y+, before boarding, the Gate agent said you have been upgraded and given a Club World seat. the Flight got delayed after 8 Hrs on the tarmac due to weather. the J seat made it easy, Slept thru most of it. when the Flight got rescheduled after 14+ hrs, the kept the original seat assignment and had a pleasant trip. I eventually missed my connection in LHR, but the BP from Biz class helped a bit with shorted queue for rebooking and using the express line at Immigration in LHR.