Admiral Dreyer, writing later about the battle, during which he had been captain of the British flagship "Iron Duke", estimated that effective shells as later introduced would have led to the sinking of six more German capital ships, based upon the actual number of hits achieved in the battle. The system of testing shells, which remained in use up to 1944, meant that, statistically, a batch of shells of which 70% were faulty stood an even chance of being accepted. Indeed, even shells that failed this relatively mild test had still been issued to ships. Analysis of the test results afterwards by the Ordnance Board suggested the likelihood that 30–70% of shells would not have passed the standard penetration test specified by the Admiralty.