She is the author of DK's The Complete Book of Spices, which enjoyed many years of success in several countries. Jill's expertise in herbs and spices has reached such a wide audience that she is frequently asked to identify spices, sent in small amounts to her by people all over the world. Other people who have bought herbs marked, vaguely, "culinary" in garden centres ring up to ask what to do with them. Recently, Encyclopedia Britannica asked Jill to be their expert to update all of their entries on herbs and spices.
Jill created the Penguin Cookery Library in the 1960s and 1970s, bringing many first-class authors to the list. She has since become a Glenfiddich trophy winner in her own right, and is a leading authority on the use of herbs and spices. She is the literary trustee of the Elizabeth David estate, and worked with Mrs David for many years. She is the author of DK's Herb & Spice.