This section is from the book "The Steward's Handbook And Guide To Party Catering", by Jessup Whitehead. Also available from Amazon: Larousse Gastronomique.
They are raised cakes, the crust of which is made of fine flour and water, with sufficient saffron to give it a deep yellow color, and the interior is filled with the materials of a very rich plum cake, with plenty of candied lemon peel and other good things. They are made up very stiff, tied up in a cloth and boiled for several hours, after which they are brushed over with eggs and then baked.. In Shropshire where simnels are an institution, a curious legend attaches to them. An old couple named Simon and Nelly, so the story goes, used up the remains of the unleavened dough provided for the fasting season, and mixed with it some plum-pudding le"ft from Christmas, and some eggs, and so made a cake for the Easter feast when their children visited them. It is said that the result was so appreciated that "Simon and Nelly Cake" became widely known; but the name was soon curtailed to "Sim Nell." As a presentation-cake nothing is more suitable than the Simnel, as, indeed, may be gathered from the following quaint rhymes in Har-land's "Lancashire Legends." The goode rounde sugarye, Kinge of cakes, a Symnelle It speaks of deareste familye tyes, From friende to friende in Lent it hyes; To all good fellowshippe yt cries, "I'm a righte trewe Symnelle." Long may symbolique symnelle send Friende's everye lovynge wishe to friende, From "Auld Lang Syne," till tyme shall ende The goode olde Symnelle.