Seat covers; seat covers for use in aircraft and other vehicles; seat covers (shaped) for use in aircraft; vehicle seat covers (fitted); vehicle seat covers (shaped); vehicle padded seat covers; seats and seating for aircraft and other vehicles; vehicle seats including aircraft seats, ejector seats, booster seats; seat backrest insert for use in aircraft; backrests for use in aircraft or transport vehicle seats; cushioned backrests for use in aircraft or transport vehicle seats; framed cushion backrest for use on vehicle seats, lounges and beds; movable backrests for use on aircraft seats