The name of this specialty comes from the fact that it originally contained plums, which it no longer does. Instead, this traditional Christmas dessert is made with suet, dried currants, raisins, almonds and spices. It's either steamed or boiled and is often served warm, flamed with brandy or rum, and accompanied by hard sauce.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.