Complex sentence: In Britain it is tradition to burn the Christmas letters on the fire so that they would be magically transported by the wind to the North Pole however this tradition is dying out in modern times with few people having true open fires in their homes.
Split into simpler sentences: In Britain it is tradition to burn the Christmas letters on the fire so that they would be magically transported by the wind to the North Pole. However, this tradition is dying out in modern times with few people having true open fires in their homes.