A revised design in March 1958 added Seaslug and Seacat missiles and added a telescopic hangar. Mountbatten staged an impressive demonstration shoot for flag officers and politicians: the Seaslug test ship HMS "Girdle Ness" launched ten successive Seaslugs, including a salvo of two Seaslugs together. The success included hits in the lethal zone of two piston-engine Fairey Firefly radio-controlled drones, at undemanding targets with a speed of only 315/375 mph. This apparent success enabled the Minister of Defence Duncan Sandys to gain the approval of the Cabinet Defence Committee for Seaslug production to be approved in 1958.