Considering that many critics, including the famous poet T.S. Eliot, have called The Moonstone the "first English detective novel," it seems strange that Sergeant Cuff, the detective, should play such a small role. He's not even the one who solves the first part of the mystery! Cuff is wrong to suspect Rachel!
But Cuff is an important character for other reasons. First of all, he sets the standard for many fictional detectives who follow, from Sherlock Holmes to television's Dr. House. Cuff is a professional detective – he is observant, intelligent, and sly, as you'd expect. But he also has some unexpected characteristics: he adores roses. Gabriel Betteredge points out that rose gardening is a strange hobby for a professional detective, and Sergeant Cuff immediately agrees. He says that that's why he does it.
So Cuff is the greatest detective in England, but still capable of making the occasional mistake. He also has some eccentricities and strange habits. Hmm, that does sound a lot like Sherlock Holmes or Dr. House. So even though Sergeant Cuff doesn't play the central role in The Moonstone that Sherlock Holmes does in Sir Arthur Conan Doyle's mysteries, he is still a very important figure in literary history: he was a source of inspiration for the great Sherlock Holmes.