A little linguistic difference
Public
The BBC TV newsreader introduced her bulletin this afternoon by wishing us "A very Happy Christmas", whereas the weather forecaster started his segment with "Merry Christmas". Not that it's of the slightest importance, but I mention it just to illustrate the fact that both phrases are in use in the UK, and although "Merry" is more common, "Happy" isn't exactly rare. (I suspect "Merry" is more common simply because it allows you to say "Merry Christmas and a Happy New Year", which is fairly frequently used.)
The BBC TV newsreader introduced her bulletin this afternoon by wishing us "A very Happy Christmas", whereas the weather forecaster started his segment with "Merry Christmas". Not that it's of the slightest importance, but I mention it just to illustrate the fact that both phrases are in use in the UK, and although "Merry" is more common, "Happy" isn't exactly rare. (I suspect "Merry" is more common simply because it allows you to say "Merry Christmas and a Happy New Year", which is fairly frequently used.)