In the older tradition (which is still kept in the liturgical calendar of the Extraordinary Form of the Mass), Christmas lasts until Candlemas, or the Feast of the Purification of the Blessed Virgin Mary and the Presentation of the Lord, which we celebrate on 2nd February.
This marked the end of a long 40-day “Christmastide” that corresponded to the 40 days of Lent. On 2nd February, the Church celebrates the day that Mary entered the Temple with the Child Jesus, when her days of purification after giving birth were fulfilled (according to the Mosaic law), and when Simeon made his well-known prophecy about Mary and the Child.
This feast is historically called “Candle-mas” because of Simeon’s prophecy of Jesus being “a light for the Gentiles.” Today, it is better known as the Feast of the Presentation of Our Lord.
Therefore, we will keep the Crib up in St Thomas’ until 2nd February, which is also the tradition at the Vatican. However, we will bring down the Christmas tree and decorations on the Feast of the Baptism of the Lord, which this year we celebrate on 9th January.