The museum docent gave us a lecture on British Christmas traditions prior to us viewing "middling class" halls decorated for Christmas across the centuries. She pointed out that all cultures have "light and warmth" holidays during the shortest daylight seasons. Ancient celebrants in Britain were fascinated with "evergreens" like firs and hollies since they appeared to stay alive when everything else was dead. Bay leaves were associated with "strength", holly with "males", and ivy with "females" - the combination meant "fertility!" One thing they would NOT have brought into their home was mistletoe which was associated with druids.
Occasionally, celebrations have been more austere (as in this 1660s photo), but mostly Brits have been eating and drinking to excess at Christmas time for centuries. They not only did not feel guilty about it (as we tend to do now) but looked forward to it. The alcoholic drinks were strong and hot. The phrase "Make a toast" came from the practice of the most honored guest taking the first slice of toast floating in the wassail bowl. "Deck" the halls meant "decorate" the halls. Beeswax (vs foul tallow) candles were burned during the 12 days of Christmas. Sugar was considered medicinal (still true today) and the lady of the house personally created amazing treats from sugar (some looked like quartered hard-boiled eggs and bacon strips).
Before the reign of Victoria and Albert, Christmas was an "adults-only" affair. But the "Hello" and "People" magazines of the time began reporting that Victoria was cutting back on business during the holidays. Pictures of Victoria and Albert gathered around the Christmas Tree (a German tradition Albert brought with him) with their children meant that Brits now wanted to include their own children in the celebrations.