Merlin has Decklock
It's bigger than a Sea King, but has much more control authority so can be accurately positioned, the RN uses a deck lock on theirs coupled with a separate deck handling system (PRISM) on frigates that can move the aircraft in/out of the hangar without external assistance. When over the grid the decklock is egnaged the deck handling system is stowed and the aircraft can then start and takeoff as normal
DM