Inspector Lestrade

Lestrade, as wiry, as dapper, and as ferret-like as ever, was waiting for us at the station.
“That he may be safely trusted to do, for although he is absolutely devoid of reason, he is as tenacious as a bulldog when he once understands what he has to do, and, indeed, it is just this tenacity which has brought him to the top at Scotland Yard.”