Christmas doesn’t end on Christmas Day—in fact, it’s just beginning for at least another 12 days, until the feast of the Epiphany! Christmas is a beautiful season in the Catholic Church, and one that liturgically really extends as far as Candlemas (also known as the feast of the Presentation of Christ in the Temple and Our Lady’s Purification) on 2nd February!*
[However], the duration of the Christmas festival was officially set at twelve days by the Council of Tours in 567 AD, where it was laid down that the whole period should be spent in celebration and thanks and that no-one could be forced to work during that time. This period of enforced rest applied even to horses, which are still blessed on the Feast of St Stephen in some parts of Europe. The period of Christmas finished at Epiphany, or “Twelfth Night.” As this decree has never been abrogated, it would appear that it is still obligatory for good Catholics to engage in the full, joyful celebration for the whole twelve days.
Under the Puritan government headed by Oliver Cromwell, all activities associated with Christmas were banned by an Act of Parliament in 1644- the very act of celebration of Christmas (“Christ’s Mass”) was seen as Catholic and therefore decadent.
Once Charles II was restored to the throne, the legislation banning Christmas was repealed and Christmas was restored, in England, at least, although the Scottish church did not ever approve. However, the celebration of Christmas in the true Catholic manner, by which the twelve days of Christmas were celebrated, together with the celebration of Epiphany, never really revived in England, which remained predominantly protestant, although Christmas as a celebration of the duration of twelve days was retained, at least in Catholic countries, in Europe.
*[Prior to the 1960 revision of the rubrics, the liturgical books of the Roman Rite did not refer to either Christmas or Epiphany as “tempora – seasons”, and indeed, neither the Missal nor the Breviary had a rubric on liturgical seasons per se. In the 1960 rubrics, within the newly-created section on the seasons of the year (title VIII), “the season of the Nativity” (tempus natalicium) is subdivided into two parts, “the season of Christmas” (tempus Nativitatis) which runs from First Vespers of Christmas to None of January 5th, and “the season of the Epiphany” (tempus Epiphaniae), which runs from First Vespers of the Epiphany to January 13th. In the body of the Missal, the Sundays after Epiphany are given a new header, “the time per annum before Septuagesima”, the forerunner of the widely detested term, “ordinary time”.]
(Sources: Venite Prandete, the New Liturgical Movement.)