In The Markenmore Mystery (1922) by J. S. Fletcher, the chief constable was talking to two lawyers about a stranger man who had gone to "Sceptre Inn" and booked a room there, but he never came back to it.
“Grimsdale asserts that the first man was an American,” remarked Walkinshaw. “We haven’t a plenitude of Americans in residence about here. I could count them on my fingers.”
“That’s so,” said the Chief Constable. “If the man was an American—and Grimsdale says he’s met a good many in his time, so he ought to know—he came from somewhere outside our neighbourhood. But what beats me is—how did he and the other man get away, unobserved, on Tuesday morning?”
Mr. Fransemmery, who, like Blick, had listened attentively, but silently, to these exchanges of opinion and idea, coughed gently, as if deprecating any idea that he wished to interfere.
“Talking of—of America,” he remarked, “it may be of no importance, and not even relative to the subject under discussion, but I may observe that a mail steamer left Southampton for New York at one o’clock on Tuesday afternoon last. Now, Markenmore is within thirty miles of Southampton by road, and if this man—the first man—was an American, it is possible that he journeyed to Southampton, caught that boat, and was away to sea before hearing of what had befallen the man whom he had entertained to supper. I know about that boat, because I mailed some antiquarian documents to a friend of mine in the United States by it.”
The Chief Constable twisted his military moustache and considered Mr. Fransemmery.
“Um!” he remarked. “Might be a good deal in that—he might certainly have taken this place in his way between London and Southampton. But—the queer thing is, we can’t hit on a trace of his coming or going!”
“Why did he never return to the Sceptre—where three pounds fourteen shillings change was due to him?” asked Walkinshaw.
I found that "a good deal" may mean "a lot", so does this sentence mean "there might be a lot of sensible details in that thought"?