Leaving Scotland Yard, the detective crossed Whitehall, automatically raising his hat to the Cenotaph as he did so. Having been too young to serve in the Great War, and having himself lost no near relations in it, he naturally did not feel the same personal interest in the national memorial as those who had, but he liked the custom of this quiet salute and always observed it. Taking a S.C. Bus, he was soon crashing down the wide thoroughfare from which the Empire is governed. Past the delicate Horse Guards building, nestling between the sombre Treasury and the great barrack of the Admiralty; past the pretentious _massif_ of the new War Office, its grossness shamed by the dignified beauty of its small neighbour “Woods and Forests”; through the lower part of Trafalgar Square, threatened now by the shadow of architectural disaster; into the whirl of one-way traffic round the Guards Crimean Memorial; through the blatant vulgarities of Piccadilly Circus and up between the glaring new commercial palaces of Regent Street; Poole at most times had an eye for London, for its beauties and its tragic blunders, but today his mind was upon the problem in front of him. Automatically he got down at Oxford Circus, disengaged himself from the “monstrous regiment” of female shoppers, and cutting across Cavendish Square, turned into the long and sombre avenue of Harley Street. “This dates him a bit, doesn’t it?” Poole muttered to himself, as he glanced up at the name of the street. Fortunately for him, Sir Horace’s house was at the Cavendish Square end, so that he was saved a possible ten minutes walk of infinite dreariness. Only one plate was on the massive door, he noticed as he rang the bell. Probably that meant that Sir Horace lived here, poor devil. The door was opened by a man-servant in a white jacket. Poole explained that he had no appointment but that, if Sir Horace had a quarter of an hour to spare in the near future, he would like to consult him upon a matter of some importance. The man-servant showed Poole into a waiting-room faintly redolent of mutton and retired, bearing with him Poole’s private card. After the customary twenty minutes wait, the man-servant returned to say that, owing to the failure of a patient, Sir Horace was fortunately able to see Mr. Poole at once—the usual formula of the unengaged.