No we don't go 7 hours without food lol. We have a nice breakfast (kids are up by 6am on a good day :p) and I do a proper lunch (ie not dinner), we always have loads of snacks like nuts, pickle, cheese, crackers etc so there is definitely no waiting about for food. Then dinner around 4pm. I do starter, roast with lots of trimmings and then a choice of deserts. I do tend to go over the top with food at Christmas though!
I always thought (and have noticed in other families) that christmas dinner is at lunchtime, but that wasn't what we wanted, the kids were nowhere near ready for a full dinner by then at all as they just never have that at lunchtimes and wouldn't enjoy it.
Just to reiterate, for us it isn't lunch!!!!! It's dinner!!!! We have a lunch and then Christmas dinner. We are used to eating at 5ish so perfect for us, if we waited any later for dinner the kids would be grumpy and starving, much like those assuming no lunch and eating for the first time at 4 lol. I've never understood making children wait until, say 7pm for dinners personally though.
I really don't see what the problem is with the way we do it, no lie ins, far from it, and the turkey takes about 5/6 hours to cook normally plus an hours standing so that fits in perfectly too.