I'm Irish back in the 40s, 50s and 60s the food was quite different compared to other years.
The one thing that hasn't changed is that we have a turkey and ham, stuffing can add sausage meat if preferred, Brussel sprouts, roast and mash potatoes, carrots. Obviously with different preferences you can leave out or add in what you like for vegetables.
Cabbage isn't always served, in early years it was, also some people had kale instead of cabbage and the leftovers were made into colcannon.
Now a days we have a variety of vegetables and some roasted instead of boiling.
Starters were served, usually soup, prawn cocktail or melon, this was I think from late 60s early 70s (my own memories) don't think there were starters before that
Dessert was Christmas pudding (the fruit one) trifle (it does have custard) later years minced pies, people made all these themselves.
Even with changing foods and different likes and dislikes and people eat all different things now, the one thing an Irish person will tell you is that we love our turkey and ham, stuffing, mash and roast potatoes and gravy.
Decorations, everyone went over the top, mixed coloured lights on the tree, shiny decorations, tinsel everywhere, walls, ceiling, around picture frames, it wasn't Christmas unless you were sitting down and a decoration fell down on your head ..
Music, from what I remember and I'm old as fuck was Christmas songs from pop singers, I don't ever recall sitting listening to hymns, I'm sure there were some that did. Abba was always playing in our house and maybe a bit of Cliff and bay city rollers.
It's tradition in most houses to have a drink Christmas morning, whiskey, port, sherry, now a days whatever you fancy whether it's alcohol or soft drink.