Neil
Many Cruisers will use a Shroud or shortened forestay with a small block attached to the end. This allows a rope to be reeved and led back to the cockpit to allow the mast to be dropped from within the boat.
I must admit I haven’t seen a bottle screw used and would think this largely overkill as the forestay becomes redundant once rig tension is applied through the jib halyard (other than to hold the mast up when halyard tension is lost/released.
David