It was not until he came nearly to Westminster Bridge that he remembered the cipher that he had prepared for Gimblet, and that he had, after all, finally left without giving it to him. It was still in his pocket, and the discovery roused him from his abstraction.
He took a taxi and drove back to the flats. A motor which had been standing before the door when he had come out was still there when he returned; so that, thinking it probably belonged to the lady he had met on the landing, and guessing that if so the detective was still occupied with her, he did not ask to see him again, but handed the envelope over to Higgs when he opened the door, with strict injunctions to take it immediately to his master.