I'm assuming these comments are from the east side of the Atlantic, so answers may differ from what they would be in North America, where most retail sales outlets operate seven days a week. Which makes it unnecessary to "move" boxing day or any other holiday.

In much of North America, though, most retail stores are open seven days a week and a large portion of the continent has never heard of "Boxing Day," which as far as I can figure out is a British holiday adopted by Canadians. Since most no-work days here are governed by local bylaws, state/provincial legislation and/or negotiated contracts, if a real holiday falls on a worker's day off, he's given another day in lieu — generally, if the holiday falls on the weekend, the Monday. That way Christmas can stay on Saturday this year, but people will get a day off on Monday. As for Boxing Day, I think Ontario has made it a statutory holiday, so the retailers who stay open have to pay their staff at an overtime rate.

After that, it gets pretty complicated.....

cheers,

david