“Yes, that was it. Mr. Hugo Oberstein, of 13 Caulfield Gardens, had become my objective. I began my operations at Gloucester Road Station, where a very helpful official walked with me along the track and allowed me to satisfy myself not only that the backstair windows of Caulfield Gardens open on the line but the even more essential fact that, owing to the intersection of one of the larger railways, the Underground trains are frequently held motionless for some minutes at that very spot.”

“Splendid, Holmes! You have got it!”