Which amateur sleuth, created by Dorothy L. Sayers, is a travelling salesman of fine wines and spirits?

Montague Egg is a fictional amateur detective, who appears in eleven short stories by Dorothy L. Sayers.

Unlike Sayers's better-known creation, Lord Peter Wimsey, Egg does not actively pursue investigations. Usually, he is witness to the discovery of a murdered body, or links a casual observation with a recent newspaper headline proclaiming some crime. He is, in his own words, 'Monty-on-the-spot'. The plots are typically neat puzzles with less personal content than the Wimsey stories, although Egg himself emerges as a memorable and likeable character. A novel would probably not have fitted the nature of the Egg stories.

By occupation, Egg is a travelling salesman for an importer and distributor of fine wines and spirits (Wimsey is a well-known connoisseur of the same). His knowledge of all aspects of the vintner's trade is useful in determining the exact circumstances of several cases of poisoning. Through regular contact with other commercial travellers, he has also gained a smattering of knowledge of several other lines of business: enough, for example, to determine (in "A Shot at Goal") that a threatening letter was written by someone connected with the printing trade rather than by a garage mechanic with a grievance, from a peculiarity of the handwriting.