Christmas until February
The main reason why the queen never takes her Christmas decorations down until February is to honor her late father. George VI passed away in his sleep on February 6th, so the queen leaves her festive ornaments up until that date every year.
The queen explained that in a way, keeping the decorations up until February 6th every year helps keep her father’s memory alive and well. It’s her personal way of celebrating her father’s accomplishments and his legacy. Each yet, the baubles, stars, and other ornaments stay in place until she commemorates the anniversary of her father’s death.