I agree that the catapult was not a permanent fitting. I think that the earlier date might have been in one of the Burt, British Battleships books. The catapult was put on the quarterdeck which was awash at full speed, even in relatively calm weather. The ship was overweight after fitting of extra armour post Jutland and she squatted down at the stern as as the speed increased. It seems that water was scooped up at the forward end of the deck and swirled around over the deck as the ship rolled, so there was no safe place for aircraft stowage.