If you are flying LHR-SAN by 747 in the winter schedule after end of Oct, it is a mid J 747 with 56J seats and you will be departing from T3. On our November flight, I paid for seats 14J/K when the flight was originally a high J with 86 J seats. My husband had the aisle and I had a window seat where I have access to the aisle without stepping over another footstool. When the plane type was changed from high J to mid J, I rebooked in 20J/K. I have no status so no upper deck seats were available.