The harpoon deck lock is a brilliant device indeed , especially when compared with the RAST paraphernalia, but much misunderstood and misused until Hermione's cab dived over the side one day, fortunately without seriously harming anyone ( I think the SMR got a belt from a piece of MRB). That changed the rules and brought the nylon lashing back into the game.
The harpoon, or more accurately, the grid, also contributed greatly to cocktail parties by providing a good spot for a fountain, if the XO could get the pipework past the FOF3 dockyard reps....
A similar device, but with a rectangular grid is also fitted to Merlin Mk1's and the T23. Don't know about the T45 - anyone help?