I have discovered that there were only five short minutes in which he could have taken it ”the five minutes immediately before our own arrival on the scene, for before that time Annie was brushing the stairs, and would have seen anyone who passed going to the right wing. 
He could only have completed it in five minutes flat if he met no hiccups. 
mnli hypothesis: He could only have completed it in five minutes flat if he met no hiccups.  premise: I have discovered that there were only five short minutes in which he could have taken it ”the five minutes immediately before our own arrival on the scene, for before that time Annie was brushing the stairs, and would have seen anyone who passed going to the right wing. 