Usually, he is witness to the discovery of a murdered body, or links a casual observation with a recent newspaper headline proclaiming some crime.
The plots are typically neat puzzles with less personal content than the Wimsey stories, although Egg himself emerges as a memorable and likeable character.
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).
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.
Egg periodically expresses admiration for the up-to-date, and in "Murder in the Morning" comments, of a prefabricated garage: "That's the stuff.... Standardisation means immense saving in labour, time, expense."