A messenger took the paper slip and departed. Uncle Brian resigned himself to another spell of tedious waiting. He had vivid recollections of Government offices in the days of the Great War, when a caller, no matter how important his business, was handed over to the tender mercies of a flapper in brown holland, and might, with luck, arrive at his destination with the last ounce of strength left in his tottering legs, only to find that after tramping through hundreds of yards of corridors the person he sought had gone to lunch. It came as an agreeable surprise when, in about five minutes, Brian Strong and his nephew were told that the Deputy Chief would see them. Their passes stamped, the two men were escorted by a messenger to a room overlooking the Mall. Here the naval officer was waiting to receive them. Sir John Pilrig was by no means the Sherlock Holmes sleuth-hound type of man that the nature of his office seemed to warrant. He was burly, full-faced, with a fresh complexion. His mild blue eyes and smooth white hair gave him a benevolent aspect, He reminded Peter more of a Harley Street specialist than a naval officer upon whose shoulders rested the weight of a responsibility hardly less than that of the First Sea Lord. There was no brusqueness in his demeanour. His manner seemed almost apologetic, but it was evident that he had the art of being able to obtain information from a person without "rubbing him up the wrong way". Sir John showed no surprise at the appearance of his callers, although their clothes, suitable to the climate of the West Indies, were hardly _comme il faut_ in Whitehall. "So you have just arrived from Rioguay, Mr. Strong?" he began. "I am pleased to meet you. I must confess that my knowledge of the internal conditions of Rioguay is elementary--I might say vague--and no doubt you may be able to give me valuable information on several points. And your friend--was he with you out there?" "My nephew--yes," replied Brian. "We left Rioguay in somewhat unusual circumstances by air." The Deputy Chief did not conceal his surprise; but he merely nodded an encouragement for Brian Strong to "carry on". Uncle Brian maintained a full head of steam for quite fifteen minutes, describing the details of the flying-boat with technical and convincing accuracy. "You know a lot of very important information about the Rioguayan air fleet," observed Sir John. "Because I designed them," was the astonishing rejoinder. "H'm," commented the Deputy Chief, without attempting to charge his visitor with unpatriotic motives. "Then with your technical knowledge, perhaps you could enlighten me on one point. Apart from the armour protection of the Rioguayan flying-boats, do they possess any special means of defence against opposing aircraft?" "Speed and manoeuvring powers," replied Brian. "Anything else?" Brian shook his head.