A landing string includes a valve having a valve member mounted within a flow path extending through the landing string, and a valve control system for use in operating the valve to move the valve member between open and closed positions to control flow along the flow path. The valve control system is reconfigurable between a first configuration in which the valve is operated or controlled under a fail-as-is (FAI) mode of operation, and a second configuration in which the valve is operated or controlled under a fail-close (FC) mode of operation.