What is the reader's impression of detective Bucket? How does Dickens accomplish his portrayal of Bucket?

Bucket is stealthy and wise He seems to eerily just appear in Tulkinghorn's office, not having used the door and being there when, a second before, no one was there. He has made no noise whatsoever, and listens attentively and quietly. He is "composed," and "sharp-eyed," and his appearance is "ghostly." Mr. Bucket makes Snagsby very nervous, but does so in a complimenting manner, feigning respect, affection and humility. Our modern-day "Columbo" character may have been based on Mr. Bucket.