one o'clock
`` No . West sat in an armchair near the writing-table ; Marden sat by the window next to the door . I had arranged that every hour one of them should go out to the gate and take the constable 's report . It was just after Marden had been out at one o'clock that it happened . `` They were sitting as I tell you when Marden thought he heard a curious sort of noise from the gate . West appeared to have heard nothing ; but I have no doubt that it was the sound of the constable 's fall . West 's pipe had gone out , and he struck a match to relight it .