The Powerhouse by John Buchan

I left Belgrave Square about a quarter to eight and retraced my steps along the route which for me that afternoon had been so full of tremors. I was still being watched -- a little observation told me that -- but I would not be interfered with, provided my way lay in a certain direction. So completely without nervousness was I that at the top of Constitution Hill I struck into the Green Park and kept to the grass till I emerged into Piccadilly, opposite Devonshire House. A light wind had risen and the evening had grown pleasantly cool. I met several men I knew going out to dinner on foot and stopped to exchange greetings. From my clothes they thought I had just returned from a day in the country.

I reached the Albany as the clock was striking eight. Lumley's rooms were on the first floor, and I was evidently expected, for the porter himself conducted me to them and waited by me till the door was opened by a manservant.