In 1919, Dickson was on an official intelligence mission in post-war Berlin. There, he met the brilliant Professor Krausse, whom he much impressed. Dickson met Krausse again, ten years later, i.e.: in 1929, when he was already an established detective at 221B Baker Street. This supports the notion that Dickson’s published cases take place from the mid-1920s to the mid- or late 1930s when he was in his late thirties and early forties, which is consistent with his physical description and abilities.