Stir up Sunday is on Sunday 26th November.
The tradition dates back to Victorian times, when the family would gather together to stir the Christmas pudding the Sunday before advent began. The opening words of the Book Of Common Prayer, read on this Sunday before Advent, are ‘Stir up, we beseech thee, O Lord’, which is probably where the name came from.
Originally Christmas pudding contained 13 ingredients said to represent Jesus and his disciples.
It is stirred by each member of the family from East to West, to remember the Wise Men that visited Jesus in the Nativity Story. This is the point where you make a wish though no-one knows when that was added to the tradition.
Charms were often added to the pud and said to bring luck if you found them in your portion on Christmas Day. Historically the lucky charms were a silver coin for wealth, a wishbone for luck, a thimble for thrift, a ring for marriage, and an anchor for safe harbour. Later coins were often used instead. As needing expensive emergency dental treatment is definitely NOT considered lucky it might be wise to forgo that particular tradition nowadays or at least give your serving a thorough inspection before you tuck in.
The traditional sprig holly on top of the pud was said to represent the crown of thorns worn by Jesus on the cross. Holly and its berries are extremely toxic so it might be better to stick to artificial greenery.
As to why we set fire to the pudding, no-one seems to know. One theory is that the flames represent the power of Christ, another is that Christian traditions mingled with the midwinter festivals of light, and the pudding, with its high alcohol content was simply a good candidate for being ignited!