There's info. on other regional carol traditions including at Leigh on Sea in the South. See:

http://news.bbc.co.uk/1/hi/magazine/8418243.stm

The problem is that there are really two aspects to the term 'traditional carols.'

One is the usual sanitised Beeb version replicated across thousands of mainly Protestant churches and cathedrals around the world.

The other is the regional carols sung with gusto in the pubs and other social gatherings such as in Yorkshire and elsewhere and more connected to the local folk song tradition than the established church.