Stir-up Sunday is an informal term in Catholic and Anglican churches for the last Sunday before the season of Advent. It gets its name from the beginning of the collect for the day in the Book of Common Prayer, which begins with the words, “Stir up, we beseech thee, O Lord, the wills of thy faithful people…”, but it has become associated with the custom of making the Christmas puddings on that day.[1] The Christmas pudding is one of the essential British Christmas traditions and is said to have been introduced to Britain by Prince Albert, husband of Queen Victoria (the reality is that the meat-less version was introduced from Germany by George I in 1714[2]). Most recipes for Christmas pudding require it to be cooked well in advance of Christmas and then reheated on Christmas Day, so the collect of the day served as a useful reminder.
Wikipedia contributors. Stir-up Sunday. Wikipedia. Published October 6, 2023. https://en.wikipedia.org/wiki/Stir-up_Sunday
Traditional Christmas Pudding Recipe