Thanks Globaliser
I think it must be, we are flying LGW/UVF, seat guru etc show the last row in PE is 15 on the 777-200ER (LGW) but on the BA manage my booking site it shows the above layout last row 16! Not quite sure why, guessing the back row would be better for sleeping as no one behind to kick your back or pull the seat when they get in or out!!