Simnel cake's English history ties it to Mothering Sunday, the fourth Sunday of Lent, which before it became a general day for honoring mothers was the day servants and apprentices, often living away from home in service, were traditionally given leave to visit their own home, or mother, church. Custom held that the strict Lenten fast could be relaxed for that one visit, and a rich fruit cake, too indulgent for an ordinary Lenten day, became the food carried home for the occasion; simnel cake, made with a layer of marzipan baked into the middle of the cake as well as on top, is the version of that visiting cake that has survived into the present. The same cake, or a freshly baked version of it, reappears weeks later at Easter itself, once Lent has ended and the fast can be broken properly, giving simnel cake an unusual double life as both a mid-fast treat, permitted as an exception to the fast rather than a violation of it, and a full feast day cake enjoyed once the fast is entirely over.
Regional versions differ, a Shrewsbury simnel is boiled before its final baking in some older recipes, while most modern versions are simply a spiced fruit cake baked once with marzipan added. The cake keeps well over several days, which suited its original purpose as a loaf carried home on a single visit rather than eaten immediately.