Mary Theresa Coolican Kelly was born in London in 1927, but ended up a Scotland gal, received an M.A. degree from University of Edinburgh in 1951, married Dennis Charles Kelly in 1950, and became a teacher. Her first mystery series featured Inspector Brett Nightingale of Scotland, starting with A Cold Coming in 1956. But after only three entries in that series, she switched to a series with freelance detective, Hedley Nicholson, as protagonist, with the first installment, The Spoilt Kill, earning the Gold Dagger Award from the British Crime Writers Association in 1961. She's also a member of the Detection Club and has served as secretary.

Apparently, starting on a new literary track worked well for her, because after only two books in the Hedley Nicholson series, she switched to standalone novels, the first three (beginning with March to the Gallows) all nominated for the Gold Dagger in 1964, 1966 and 1969. She also tried her hand at a short story in 1971, "Judgment," chosen for inclusion in 1984's anthology The Best Crime Stories published by Hamlyn, putting in her the same company as Edgar Allan Poe, Arthur Conan Doyle and Agatha Christie. Unfortunately, in 1976 she stopped writing for good.

In The Spoilt Kill, P.I. Nicholson is hired to discover who is copying new pottery designs from the Shentall Pottery Company of Stoke-on-Trent and selling them to foreign competitors. It seems fairly straightforward until a body is found in a closed "kill" (local dialect for "kiln") filled with liquid clay. Nicholson soon finds himself falling for the chief suspect in both crimes, talented designer Corina Wakefield, the only employee not native to the area—who also has a drinking problem and a failed marriage that turns out to be relevant to the case.

Kelly structures the plot to start off with the discovery of the body in the first section ("What Happened"), just one chapter, in essence a prologue, then doubles back to a prequel of events ("What Happened Before") in the middle section, before returning to the denouement in part three's "What Happened After." The author does a nice job of immersing the reader into the atmospheric setting of the industrial area in the Midlands and of the pottery world, with passages such as the following:

"...A row of bottle kilns blocking the gap between blackened brick buildings, and beyond them a factory chimney and the peak of a slag heap, wraiths even in the middle distance. There was no far distance, only a grey blankness of cleaned smoke mixed with the drizzle that seeped from low-lying clouds."

Kelly had a foot in the very end of the Golden Age of detective fiction, and was a somewhat rare example of a female British writer penning a professional male private eye. As such, Spoilt Kill has the feel of a hybrid cozy/traditional mystery blended with the P.I. form. Some may quibble that Kelly doesn't quite nail the male first-person POV all the time, and the ending a tad telescoped, but the characters are well drawn and engaging, and the true mystery Kelly portrays is the psychological puzzle underlying human relationships.